# Down the ballot: report

Chapter 6.4 of The Public Mind, by Vishal Singh (NYU Stern). Generated from the chapter's data files; the reading version is at https://vishalsingh.org/politics/down-the-ballot. Table n of this report is figure n of the chapter.

## Identification

- Title: Down the ballot
- Chapter: 6.4 (Part VI, Election results at different scales; Votes, giving and places)
- Question: How much ticket splitting remains, among voters and among counties?
- Dek: Among ANES voters who reported major-party votes for president and the House, 4.7% chose different parties in 2024, against 22.3% in 1992 and 29.5% in 1972.
- Grain: places
- Status: draft
- Published: 2026-10-03
- Updated: not revised
- Data sources:
  - ANES Cumulative Data File. Cumulative Data File 1948-2024: president, House and Senate vote items (VCF0704, VCF0707, VCF0708), combined item VCF0709 for 1952 to 2020; post-election weight; mode weights for 2008, 2012, 2016 and 2024; years: 1948-2024 (33 study years; even years only after 2004; no 2006, 2010 or 2014 study); weights: weight_postelection (VCF9999) where the file has it and VCF0009z elsewhere (VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988); weight_ftf and weight_web for the mode split
  - County election returns. County returns for President, U.S. House and U.S. Senate, 1992-2024, 48 contiguous states (Heideman 2026, summary and candidate-level files); years: President 1868-2024 (40 elections); House and Senate 1990-2024; weights: none (full counts); vote-weighted statistics weight each county by its presidential two-party votes
  - State presidential returns. State presidential returns, 2024, certified national Democratic share of the two-party vote (benchmark for the ANES 2024 sample); years: 1976-2024 (13 elections); weights: none (full counts)
- Canonical URL: https://vishalsingh.org/politics/down-the-ballot
- Report: https://vishalsingh.org/politics/down-the-ballot/report
- Markdown: https://vishalsingh.org/politics/down-the-ballot/report.md
- BibTeX key: singh2026downtheballot

```bibtex
@misc{singh2026downtheballot,
  author = {Singh, Vishal},
  title = {Down the ballot},
  year = {2026},
  url = {https://vishalsingh.org/politics/down-the-ballot},
  note = {In The Public Mind. Published 3 October 2026.}
}
```

## Principal estimates

The facts the dek and the opening prose cite, in order of appearance.

| Estimand | Population | Period | Value | Interval | n | Weights | Source | Fact id |
| --- | --- | --- | ---: | --- | ---: | --- | --- | --- |
| weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 4.7% | 95% CI 3.7% to 5.7% | 3,515 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File | split_h_2024 |
| weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1992 | 22.3% | 95% CI 19.9% to 24.8% | 1,126 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File | split_h_1992 |
| weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1972 | 29.5% | 95% CI 27.1% to 32.0% | 1,293 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File | split_h_1972 |
| count of studies with the president and House vote items | ANES presidential-election studies | 1952-2024 | 19 |   |   | none (count) | ANES Cumulative Data File | n_studies |
| share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2024 | 2.8% |   | 2,695 | none (full counts) | County election returns | house_div_2024 |
| count of counties in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 2024 | 2,695 |   |   | none (full counts) | County election returns | n_house_2024 |
| share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 1992 | 31.0% |   | 2,735 | none (full counts) | County election returns | house_div_1992 |
| count of counties in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 1992 | 2,735 |   |   | none (full counts) | County election returns | n_house_1992 |
| count of respondents with a post-election weight in the 19 studies | respondents who reported a major-party presidential vote and a major-party House vote | 1952-2024 | 29,103 |   |   | none (count) | ANES Cumulative Data File | n_house |
| count of respondents with a post-election weight in the 19 studies | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 1952-2024 | 20,334 |   |   | none (count) | ANES Cumulative Data File | n_senate |
| count of counties with presidential two-party votes | counties in the 48 contiguous states with presidential votes | 2024 | 3,107 |   |   | none (full counts) | County election returns | n_pres_counties_2024 |
| count of presidential elections compared | presidential elections in the county file | 1992-2024 | 9 |   |   | none (full counts) | County election returns | n_elections |

## Findings

In 2024, 4.7% (95% CI 3.7% to 5.7%) of voters in the American National Election Studies (ANES) who reported a major-party vote for president and for the House chose candidates of different parties. The rate was 22.3% (95% CI 19.9% to 24.8%) in 1992 and 29.5% (95% CI 27.1% to 32.0%) in 1972, the highest rate among the 19 studies from 1952 to 2024. In county returns, the presidential and House winners differed in 2.8% of the 2,695 counties in which every district part of the House race was contested in 2024, against 31.0% of 2,735 counties in 1992.

Ticket splitting is a vote for one party's candidate for one office and for another party's candidate for a second office on the same ballot. The ANES asks respondents for both votes, so it measures splitting directly, by self-report, and the reported 2024 presidential vote leans Democratic against the certified count (the last section gives the figures). (Note: The individual sample is 29,103 respondents in 19 presidential-election studies from 1952 to 2024 who reported a major-party vote for president and the House, and 20,334 who reported one for president and the Senate. Estimates use the survey weight and intervals use the Kish effective sample size [1], which treats the weighted sample as a simple random sample.) County returns count each candidate's votes in a place and never match one voter's two choices. They show how often the two winners in a county differed. Splitting can produce that result, but the two races also draw different numbers of voters, and splits in opposite directions cancel in a county total. This chapter calls a county whose presidential and House winners differ a divided county. (Note: The county sample is the contiguous states, with 3,107 counties holding presidential votes in 2024, in the 9 presidential elections from 1992 to 2024. The rules for which counties enter each comparison are given below and in the methods note.) Chapter 6.1, Nationalization of the county vote (https://vishalsingh.org/politics/nationalization-of-the-county-vote) measures how uniformly counties moved between presidential elections; this chapter compares two offices in the same election.

Burden and Kimball [2] studied presidential, House and Senate voting from 1952 to 1996. They linked ticket splitting to the similarity of the candidates' platforms, to candidate characteristics and to changes in congressional campaigns such as the rise of incumbency advantage and of money, and not to voters balancing the parties. Jacobson [3] reports that the electoral advantage of House incumbents fell to levels not seen since the 1950s, together with an increase in party loyalty, straight-ticket voting and president-centered nationalization. Hopkins [4] documents the nationalization of American political behavior. Kuriwaki [5] uses cast vote records, which show one voter's choices across offices, and finds ticket splitting higher in state and local offices than in Congress. This chapter describes how much splitting there is for Congress and does not test any of these explanations.

### Self-reported splitting was highest from 1972 to 1988 and lowest in 2024

Table 1 plots the share of voters who split between president and House, with the Senate beside it. From 1952 to 1968 the president and House rate was between 12.6% and 17.8% in every study. It was 29.5% (95% CI 27.1% to 32.0%) in 1972 and between 24.8% and 29.5% in each study from 1972 to 1988. In 1992 it was 22.3% (95% CI 19.9% to 24.8%), and in each study from 1996 to 2008 it was between 16.7% and 18.3%. The later studies give 9.8% (95% CI 8.5% to 11.1%) in 2012, 15.3% (95% CI 13.4% to 17.1%) in 2016, 11.4% (95% CI 10.1% to 12.6%) in 2020 and 4.7% (95% CI 3.7% to 5.7%) in 2024. The 2024 interval lies below the interval of every earlier study. The rate was 6.7 (95% CI 5.1 to 8.2) points lower in 2024 than in 2020, 17.7 (95% CI 15.0 to 20.3) points lower than in 1992 and 24.9 (95% CI 22.2 to 27.5) points lower than in 1972.

Table 1. Self-reported ticket splitting between president and House fell from 29.5% of voters in 1972 to 4.7% in 2024

The cumulative file's combined president and House item (VCF0709) is missing for 2024, so every year here uses a split rebuilt from the presidential vote item (VCF0704) and the House vote item (VCF0707). The rebuilt code covers 3,530 respondents in 2024. In the 18 studies where VCF0709 exists, it equals the rebuilt code for all 25,637 respondents who have both. The 2 respondents in 1984 who have VCF0709 but a missing vote item are left out. The vote items are post-election, so estimates use the post-election weight in the studies that have one and the full-sample weight in the others, 2012 included. 64 respondents with both votes in 2016, 2020 and 2024 lack the post-election weight and are left out.

The president and Senate rate is close to the House rate in level, with a correlation of +0.94 across the 19 studies, but it does not move with it at every step. It was 28.5% (95% CI 25.3% to 31.7%) in 1972, 7.2% (95% CI 5.9% to 8.5%) in 2020 and 6.8% (95% CI 5.4% to 8.3%) in 2024, with overlapping intervals for 2020 and 2024. The Senate item is asked only where the respondent's state held a Senate race. The fall since 2008 is not smooth for the House. The rate dropped by 6.9 (95% CI 4.0 to 9.8) points between 2008 and 2012, rose in 2016 and dropped again by 2024. The 2008 to 2012 fall crosses the addition of the web sample. Among in-person respondents alone the rate went from 16.8% (95% CI 14.2% to 19.4%) to 11.0% (95% CI 8.5% to 13.6%), a fall of 5.7 (95% CI 2.1 to 9.4) points, so the fall is not solely a change of mode. The Senate rate did not fall over those years. It was 12.9% (95% CI 9.9% to 15.9%) in 2008 and 11.1% (95% CI 9.5% to 12.6%) in 2012, a change of −1.8 (95% CI −5.2 to 1.6) points with an interval that includes zero.

### The 2016 rise appears among web respondents in the House item

The ANES interviewed respondents mostly in person through 2008 and added a web sample alongside the in-person sample in 2012, 2016 and 2024. The 2020 study has no separate weights by interview mode, so it enters only the all-interview series. The all-interview rate for the House rose from 9.8% in 2012 to 15.3% in 2016, a change of +5.5 (95% CI 3.2 to 7.7) points. The rise is larger among web respondents, who moved from 9.2% (95% CI 7.7% to 10.7%) to 17.4% (95% CI 15.1% to 19.6%), a change of +8.2 (95% CI 5.4 to 10.9) points. In-person respondents moved from 11.0% (95% CI 8.5% to 13.6%) to 10.2% (95% CI 7.2% to 13.1%), a change of −0.9 (95% CI −4.8 to 3.1) points. That interval includes zero and also a rise of several points, so the data do not confine the rise to the web sample.

Table 2 compares the two modes within each study. In 2016 web respondents split more than in-person respondents by +7.2 (95% CI 3.4 to 10.9) points for the House. The Senate item shows less. Web minus in-person was +3.7 (95% CI −0.6 to 8.0) points in 2016, +1.1 (95% CI −2.2 to 4.4) in 2012 and −1.7 (95% CI −5.8 to 2.5) in 2024, and the web change from 2012 to 2016 was +2.5 (95% CI −0.5 to 5.5) points. All four intervals include zero, so the 2016 jump is clear in the House item and not in the Senate item. For the House, the difference was −1.9 (95% CI −4.9 to 1.1) points in 2012 and −0.3 (95% CI −3.2 to 2.7) points in 2024, when in-person respondents split at 5.3% (95% CI 2.8% to 7.8%) and web respondents at 5.0% (95% CI 3.4% to 6.6%). Both of those intervals include zero and exclude a gap the size of the 2016 gap. Both still allow differences of a few points, which is wide against a rate near 4.7%. The fall from 2016 to 2024 appears in both modes, at 4.9 (95% CI 1.0 to 8.8) points among in-person respondents and 12.4 (95% CI 9.6 to 15.2) points among web respondents.

Table 2. Web respondents reported more ticket splitting than in-person respondents for the House in 2016 by +7.2 points, against −1.9 in 2012 and −0.3 in 2024

The two modes are separately recruited samples, so the comparison cannot separate an effect of the interview mode from a difference between the people who answered. The mode estimates use the in-person and web weights, because the file has no post-election mode weights. The 2024 mode weights cover only the newly recruited samples. The 1,709 panel and paper respondents with both votes are in neither mode, and they split at 3.7% (95% CI 2.4% to 4.9%), which is why the all-interview rate for 2024 sits below the rate in each mode. The fall from 2020 to 2024 is read from the all-interview series because 2020 has no mode weights.

### Republican president, Democratic House was the usual split from 1972 to 1988

Table 3 separates the two kinds of split. Voters who chose a Republican for president and a Democrat for the House were 25.0% (95% CI 22.6% to 27.3%) of voters in 1972 and 18.3% (95% CI 15.9% to 20.6%) in 1988. In every study from 1972 to 1988 that line is above the other kind, with separate intervals. In 1996 the order reversed, with 13.4% (95% CI 10.9% to 15.8%) choosing a Democrat for president and a Republican for the House against 4.3% (95% CI 2.8% to 5.7%) for the opposite combination. From 1996 on the Democratic-president, Republican-House kind has the higher estimate in 7 of the 8 studies. The intervals separate only in 1996 and 2020, when the two kinds were 6.8% (95% CI 5.8% to 7.8%) and 4.6% (95% CI 3.8% to 5.4%). In 2024 they are 3.0% (95% CI 2.2% to 3.8%) and 1.7% (95% CI 1.1% to 2.3%).

Splits in opposite directions offset each other in a vote total, so the net effect on the House vote is smaller than the share who split. Among the same voters, the House Democratic share minus the presidential Democratic share was +20.4 (95% CI 17.7 to 23.2) points in 1972 and −9.1 (95% CI −12.0 to −6.1) points in 1996, when the House vote was less Democratic than the presidential vote. In 1992 22.3% of voters split, and the net difference was +2.1 (95% CI −0.6 to 4.9) points, an interval that includes zero. In 2024 it was −1.3 (95% CI −2.3 to −0.2) points. The second view of the figure plots this net effect.

Table 3. Voters who chose a Republican for president and a Democrat for the House were 25.0% in 1972 and 1.7% in 2024

### The divided-county share fell from 2008 to 2012 and again by 2020

A county is divided when the party that won more of the Democratic and Republican presidential votes differs from the party that won more of the House votes. The comparison needs rules for races without a real contest and for defects in the county file. A county is left out for an exact tie. Jackson County, Missouri, is left out in the 6 elections from 2004 to 2024, because the file leaves out the part of the county in Kansas City. Senate races in which the file codes an independent as a major-party candidate (Maine and Vermont in 2012 and Nebraska in 2024, 123 county-years) are left out, because the file codes the same candidates as independents in other years.

A totals screen leaves out county rows whose House or Senate total votes fall outside 0.7 to 1.3 times the presidential total. It removes 687 of 27,567 House county-years (2.5%) and 398 of 18,645 Senate county-years (2.1%). The named defects are the Iowa 2012 House file, which double counts the votes (99 counties), the Georgia Senate vote in 1992 and 2008, where the file holds a later runoff round (158 and 157 counties), and the Louisiana Senate vote in 1992, which is the October primary (61 counties). The other 588 House and 22 Senate county-years have totals far from the presidential total for reasons the file does not give. Of the House ones, 150 would otherwise be in the main sample. Dropping the screen changes the yearly share of divided counties by at most 0.5 points for the House and 1.3 points for the Senate.

A race is a two-party race when the Democratic and Republican candidates together won at least 80% of its votes. The rule leaves out races with a strong independent, and it fails in 14 House races and 1 Senate race with candidates of both parties. A race is contested when both candidates received votes. A House race is a district. A county enters the main sample only when every district part of it was a contested two-party race, because a county that holds parts of several districts sums parts of several races. A Senate race is a state. Among the county-years that pass the first two rules, the race rules remove 3,097 House and 295 Senate county-years. A second sample, all returns, keeps the counties in uncontested two-party races.

Table 4 plots the share of divided counties in the House sample. It was 31.0% in 1992, among 2,735 counties, and stayed between 25.5% and 31.0% in every election through 2008. It was 9.7% in 2012, which is 16.9 points below 2008, 7.7% in 2016, 3.0% in 2020 and 2.8% in 2024. No election after 2008 exceeded 9.7%. Weighted by votes, the divided counties held 27.9% of the presidential two-party votes cast in the sample in 1992 and 5.5% in 2024, so the divided counties of 2024 were larger than the typical county. Keeping the counties in uncontested races gives 30.6% in 1992 and 2.7% in 2024. It changes the county share by at most 2.1 points in any election, the largest change being in 2004.

Table 4. Counties whose presidential and House winners differed fell from 31.0% of counties in 1992 to 2.8% in 2024

The Senate fall comes later in the pooled series. The share of counties divided between president and Senate was 30.9% in 1992, 29.6% in 2004 and 24.4% in 2008, then 18.2% in 2012, 6.2% in 2016, 1.9% in 2020 and 3.0% in 2024. It fell by 6.2 points from 2008 to 2012 and by 11.9 points from 2012 to 2016, against 16.9 points for the House from 2008 to 2012. The Senate sample is the 29 states with a contested regular race in 2024 and differs from election to election, so that comparison mixes states. The cleaner comparison is by Senate class, the seats that come up together, so that the same states vote in every third presidential election. In the class that voted in 2000, 2012 and 2024 the share of divided counties was 21.1%, 18.2% and 3.0%. In the class of 1996, 2008 and 2020 it was 20.2%, 24.4% and 1.9%, and in the class of 1992, 2004 and 2016 it was 30.9%, 29.6% and 6.2%. In each class the latest of the three elections has the lowest share. That pattern is consistent with a fall after 2008 or 2012 and does not date it.

### Divided counties mostly had a Republican president and a Democratic House

The direction views of Table 4 count the divided counties of each kind. Counties with a Republican for president and a Democrat for the House outnumbered the reverse in 7 of the 9 elections. The exceptions are 1996 and 2020. The counts were 573 against 276 in 1992, 226 against 466 in 1996, 40 against 47 in 2020 and 49 against 27 in 2024. In the Senate the Republican-president kind led in 6 elections, and the reverse led in 1992, 1996 and 2020, with 369 against 94 in 1996 and 22 against 21 in 2020. In 2024 the Senate counts were 45 and 8. The House exceptions, 1996 and 2020, are also the two studies in which the ANES intervals separate with the Democratic-president kind larger. In most other years after 1996 the ANES point estimates favor that kind while the county counts favor the opposite. The two count different things, voters and county winners, and counties weigh a small county as much as a large one.

Table 5 colors each county in the sample by its two winners. In 1992 the share of counties that were divided was 32.5% in the Census Bureau's South and 29.9% in the rest of the country. In 2004 the South's share was higher, at 30.5% against 22.2%. In 2012 and 2016 it was lower, at 7.6% against 11.2% and 5.1% against 9.6%. In 2024 the two shares were 2.9% and 2.7%. The South stood out in some elections and not in others, in both directions.

Table 5. Counties with different presidential and House winners were spread across regions in 1992, 32.5% of the South's counties and 29.9% of the other regions' counties

### County margins converged on the presidential margin

A second view of the same counties compares margins and not winners. Table 6 plots the correlation across counties between the two-party margin for president and the margin for the House, weighted by presidential votes. It was +0.65 (95% CI 0.56 to 0.72) in 1992 and +0.82 (95% CI 0.76 to 0.86) in 2008. It reached +0.95 (95% CI 0.93 to 0.96) in 2012, +0.99 (95% CI 0.98 to 0.99) in 2020 and +0.99 (95% CI 0.99 to 0.99) in 2024. The county-equal correlation, which counts each county once, was +0.58 (95% CI 0.47 to 0.67) in 1992 and +0.98 (95% CI 0.98 to 0.99) in 2024. For the Senate the correlation was +0.63 (95% CI 0.47 to 0.79) in 1992 and +0.98 (95% CI 0.97 to 0.99) in 2024. The intervals resample whole states, so they show how much each value depends on which states are in the sample.

Table 6. The correlation between county presidential and House margins rose from +0.65 in 1992 to +0.99 in 2024

A correlation measures whether counties keep their order, and it would be high if every county's House margin were its presidential margin plus a constant. The second view of the figure plots the size of the gap in points. The vote-weighted average absolute gap between the House margin and the presidential margin was 16.4 (95% CI 14.5 to 18.7) points in 1992 and 3.7 (95% CI 3.2 to 4.2) points in 2024. For the Senate it was 15.9 (95% CI 12.1 to 21.1) points in 1992 and 4.6 (95% CI 3.4 to 6.0) points in 2024.

### Most of the gap is a district-wide or statewide shift

The gap between the down-ballot margin and the presidential margin can be split into the average gap of the district or state a county sits in, and the variation among counties inside it. Table 7 plots the root mean square of the gap, which weights large gaps more than the average absolute gap does, and the root mean square of what remains once each district's or state's average is removed. The House gap, for counties wholly inside one district, was 27.0 points in 1992 and 5.5 points in 2024. The part that varies among counties inside a district was 9.1 and 2.3. The district average is 89% of the mean square of the gap in 1992 and 83% in 2024, and it is between 82% and 94% in every election. For the Senate the gap in 2024 was 6.1 points, and 2.5 points of it varied inside states. The state average is between 64% and 91% of the mean square across elections and 83% in 2024.

Table 7. A shift shared by the counties of one district or state accounts for most of the gap between presidential and down-ballot margins

These shares use districts and states with more than one county in the sample, and they correct the part inside each unit for the number of counties, because a unit's own average absorbs part of its counties' deviations. Without the correction the House share is between 84% and 94%. A county's down-ballot result therefore differs from its presidential result mostly by an amount that its neighbors in the same district or state share. The data describe where the gap lies and not what produces it.

### Both measures fell from 2008 to 2012 and then parted

Table 8 puts the two measures on one scale for the nine presidential elections. The share of ANES voters who split between president and House fell from 22.3% in 1992 to 4.7% in 2024, a fall of 17.7 points, and the share of divided counties fell by 28.2 points. Both fell between 2008 and 2012, from 16.7% to 9.8% for voters and from 26.6% to 9.7% for counties. They then part. The voter rate rose to 15.3% in 2016, the House-item rise of the mode section, while the county share fell to 7.7%.

Table 8. Between 1992 and 2024 the share of ANES voters who split their ticket fell by 17.7 points and the share of divided counties by 28.2 points

The two lines are shares of different things and cannot be derived from each other. A county can be divided with few voters splitting, if its two races were close and drew different electorates, and a county can have a high rate of splitting with the same winner in both races, if splits run in both directions. The ANES records a respondent's state and no county, so it cannot say which kinds of place have the most individual splitting.

### Which counties are in the comparison

Table 9 lists the counties and the votes behind each main sample, with the share of divided counties for the House and the Senate. The House sample holds between 71% and 84% of the presidential two-party votes of the contiguous states, and 81% in 2024. The rest are in counties with an uncontested race, no usable returns in the file or a failed totals screen. The Senate sample holds between 49% and 74% because only states with a contested regular Senate race enter. Keeping the counties in uncontested Senate races changes the share of divided counties by at most 1.0 points in any election.

Table 9. The main House sample holds between 71% and 84% of the presidential votes of the contiguous states and the main Senate sample between 49% and 74%

### What these data cannot show

County returns cannot identify who splits a ticket. A county in which the two winners agree can contain many voters who split in opposite directions, and a divided county can arise from close races and unequal turnout with few splitters. Robinson [6] showed that a correlation across places can differ in size and sign from the relationship among the individuals who live in them. The ANES has state geography only, so it cannot say where individual splitting is highest. Amlani and Algara [7] study nationalization in county presidential, senatorial and gubernatorial returns from 1872 to 2020, a longer period and a different measure than the comparisons here.

The ANES measure is self-reported. Respondents describe their votes after the election, and the file has no validated vote. The ANES voters in the 2024 sample are 55.3% (95% CI 53.0% to 57.7%) Democratic in the major-party presidential vote against 49.2% in the certified national count, so self-reported votes lean Democratic. A lean that differed between voters who split and voters who did not would change the rate of splitting, and the chapter cannot say whether it does. The samples are respondents who reported a major-party vote in both races, so voters who chose a third-party candidate, left a race blank or did not vote are out. The Cooperative Election Study file used in this book has no House, Senate or governor vote choice, so it gives no second individual-level source for 2006 to 2024. The full cumulative file has those items and would add that check, but it is not part of this build.

The chapter describes and does not explain. Incumbency, candidate quality and redistricting are possible reasons for the fall in divided counties and for the shared shifts by district and state, and nothing here tests them. The county fall from 2008 to 2012 comes between two elections separated by the 2010 midterm and by redistricting after the 2010 census, and timing alone does not say which of these matters, if any. Planned, Candidate extremity and vote share (https://vishalsingh.org/politics/candidate-extremity-and-vote-share; planned), a planned chapter, asks whether more extreme House candidates lose vote share. The county file holds only president, House and Senate, so it says nothing about governors, state legislators or local offices, where Kuriwaki [5] finds more splitting than in Congress.

The county comparison depends on its rules and on the file. The main sample leaves out uncontested races, and uncontested seats are not a random draw of places. The file has defects that the rules remove or work around, such as the missing Kansas City part of Jackson County, runoffs stored as general elections and an Iowa file that double counts votes, and others may remain. The House samples use different district maps in different decades, and the Senate samples use different states in different elections. Presidential margins leave out third-party votes, which were a larger share of the vote in 1992 and 1996 than in later elections. Alaska and Hawaii are not in the county file. County returns are full counts and carry no sampling interval. The intervals on the correlations treat states as independent, and the shared-shift decomposition describes where the gap lies without saying why it lies there.

## Tables

### Table 1. Self-reported ticket splitting between president and House fell from 29.5% of voters in 1972 to 4.7% in 2024

Share of voters who reported different parties' candidates for president and for the House (or Senate), voters with a major-party vote in both races, ANES studies 1952 to 2024; 95% intervals

| Races | Interview mode | Study | Share who split (%) | Lower | Upper | Respondents |
| --- | --- | ---: | ---: | ---: | ---: | ---: |
| President and House | all | 1952 | 12.6 | 10.5 | 14.6 | 1,009 |
| President and House | all | 1956 | 15.6 | 13.5 | 17.6 | 1,151 |
| President and House | all | 1960 | 14.0 | 11.1 | 16.9 | 766 |
| President and House | all | 1964 | 15.1 | 12.8 | 17.4 | 947 |
| President and House | all | 1968 | 17.8 | 15.1 | 20.5 | 776 |
| President and House | all | 1972 | 29.5 | 27.1 | 32.0 | 1,293 |
| President and House | all | 1976 | 24.8 | 22.1 | 27.4 | 1,049 |
| President and House | all | 1980 | 27.7 | 24.5 | 30.9 | 762 |
| President and House | all | 1984 | 25.4 | 22.9 | 27.9 | 1,142 |
| President and House | all | 1988 | 25.3 | 22.7 | 28.0 | 1,030 |
| President and House | all | 1992 | 22.3 | 19.9 | 24.8 | 1,126 |
| President and House | all | 1996 | 17.7 | 14.9 | 20.4 | 926 |
| President and House | all | 2000 | 18.3 | 15.5 | 21.2 | 882 |
| President and House | all | 2004 | 16.8 | 13.8 | 19.8 | 701 |
| President and House | all | 2008 | 16.7 | 14.1 | 19.3 | 1,222 |
| President and House | all | 2012 | 9.8 | 8.5 | 11.1 | 3,501 |
| President and House | all | 2016 | 15.3 | 13.4 | 17.1 | 2,138 |
| President and House | all | 2020 | 11.4 | 10.1 | 12.6 | 5,167 |
| President and House | all | 2024 | 4.7 | 3.7 | 5.7 | 3,515 |
| President and House | ftf | 2008 | 16.8 | 14.2 | 19.4 | 1,222 |
| President and House | ftf | 2012 | 11.0 | 8.5 | 13.6 | 1,065 |
| President and House | ftf | 2016 | 10.2 | 7.2 | 13.1 | 619 |
| President and House | ftf | 2024 | 5.3 | 2.8 | 7.8 | 579 |
| President and House | web | 2012 | 9.2 | 7.7 | 10.7 | 2,436 |
| President and House | web | 2016 | 17.4 | 15.1 | 19.6 | 1,519 |
| President and House | web | 2024 | 5.0 | 3.4 | 6.6 | 1,227 |
| President and Senate | all | 1952 | 12.0 | 9.8 | 14.3 | 797 |
| President and Senate | all | 1956 | 16.1 | 13.6 | 18.5 | 878 |
| President and Senate | all | 1960 | 11.1 | 7.7 | 14.5 | 455 |
| President and Senate | all | 1964 | 17.2 | 14.5 | 19.8 | 787 |
| President and Senate | all | 1968 | 19.2 | 16.1 | 22.4 | 603 |
| President and Senate | all | 1972 | 28.5 | 25.3 | 31.7 | 765 |
| President and Senate | all | 1976 | 23.6 | 20.5 | 26.6 | 768 |
| President and Senate | all | 1980 | 23.7 | 20.2 | 27.3 | 539 |
| President and Senate | all | 1984 | 22.7 | 19.7 | 25.8 | 717 |
| President and Senate | all | 1988 | 23.3 | 20.4 | 26.2 | 819 |
| President and Senate | all | 1992 | 19.2 | 16.4 | 21.9 | 795 |
| President and Senate | all | 1996 | 14.7 | 11.4 | 18.0 | 548 |
| President and Senate | all | 2000 | 14.0 | 11.2 | 16.8 | 726 |
| President and Senate | all | 2004 | 14.5 | 11.2 | 17.9 | 508 |
| President and Senate | all | 2008 | 12.9 | 9.9 | 15.9 | 786 |
| President and Senate | all | 2012 | 11.1 | 9.5 | 12.6 | 2,814 |
| President and Senate | all | 2016 | 13.0 | 11.0 | 15.0 | 1,625 |
| President and Senate | all | 2020 | 7.2 | 5.9 | 8.5 | 2,879 |
| President and Senate | all | 2024 | 6.8 | 5.4 | 8.3 | 2,525 |
| President and Senate | ftf | 2008 | 12.8 | 9.9 | 15.8 | 786 |
| President and Senate | ftf | 2012 | 10.4 | 7.6 | 13.1 | 837 |
| President and Senate | ftf | 2016 | 10.3 | 6.7 | 13.9 | 447 |
| President and Senate | ftf | 2024 | 7.9 | 4.4 | 11.4 | 433 |
| President and Senate | web | 2012 | 11.5 | 9.6 | 13.3 | 1,977 |
| President and Senate | web | 2016 | 14.0 | 11.6 | 16.4 | 1,178 |
| President and Senate | web | 2024 | 6.2 | 4.1 | 8.3 | 923 |

Views: All interviews (mode = all); In person (mode = ftf); Web (mode = web).

Note: The 2024 president and House estimate is rebuilt from the presidential and House vote items because the cumulative file's combined item (VCF0709) is missing for 2024. In the 18 earlier studies the rebuilt code equals VCF0709 for all 25,637 respondents with both.

Note: The Senate item is asked only where the respondent's state had a Senate race. The 2020 study has no mode weights, so the mode views leave 2020 open. The all-interview estimates use the post-election weight in the studies that have one and VCF0009z in the others, 2012 included; the mode estimates use the in-person and web weights. Weights equal one in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988.

Source: ANES Cumulative Data File, 1952-2024; weighted (post-election weight where the file has one, VCF0009z elsewhere; mode weights weight_ftf and weight_web for 2008, 2012, 2016 and 2024)

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/split_by_year.json

### Table 2. Web respondents reported more ticket splitting than in-person respondents for the House in 2016 by +7.2 points, against −1.9 in 2012 and −0.3 in 2024

Share of voters who reported different parties' candidates for president and the House (or Senate), by interview mode, ANES 2012, 2016 and 2024; 95% intervals

| ftf | ftf_hi | ftf_lo | label | n_ftf | n_web | web | web_hi | web_lo |
| ---: | ---: | ---: | --- | ---: | ---: | ---: | ---: | ---: |
| 11.04 | 13.62 | 8.45 | House, 2012 | 1,065 | 2,436 | 9.18 | 10.69 | 7.66 |
| 10.17 | 13.15 | 7.18 | House, 2016 | 619 | 1,519 | 17.35 | 19.62 | 15.09 |
| 5.27 | 7.76 | 2.79 | House, 2024 | 579 | 1,227 | 5.00 | 6.63 | 3.36 |
| 10.36 | 13.09 | 7.63 | Senate, 2012 | 837 | 1,977 | 11.47 | 13.33 | 9.60 |
| 10.28 | 13.85 | 6.71 | Senate, 2016 | 447 | 1,178 | 14.01 | 16.37 | 11.65 |
| 7.88 | 11.41 | 4.35 | Senate, 2024 | 433 | 923 | 6.23 | 8.34 | 4.11 |

Note: The 2024 mode weights cover the newly recruited in-person and web samples. The 1,709 voters in the panel and paper samples belong to neither mode row.

Note: The 2020 study has no mode weights and is not shown. The file has no post-election mode weights, so these estimates use the full-sample in-person and web weights.

Source: ANES Cumulative Data File, 2012, 2016 and 2024; weighted (weight_ftf and weight_web)

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/split_by_mode.json

### Table 3. Voters who chose a Republican for president and a Democrat for the House were 25.0% in 1972 and 1.7% in 2024

Share of voters with a major-party vote for president and for the House, by which party won each vote, ANES studies 1952 to 2024; 95% intervals

| View | Measure | Study | Estimate | Lower | Upper | Respondents |
| --- | --- | ---: | ---: | ---: | ---: | ---: |
| direction | Republican for president, Democratic for House | 1952 | 10.3 | 8.4 | 12.2 | 1,009 |
| direction | Republican for president, Democratic for House | 1956 | 13.5 | 11.5 | 15.4 | 1,151 |
| direction | Republican for president, Democratic for House | 1960 | 9.8 | 7.3 | 12.3 | 766 |
| direction | Republican for president, Democratic for House | 1964 | 6.4 | 4.9 | 8.0 | 947 |
| direction | Republican for president, Democratic for House | 1968 | 10.8 | 8.6 | 13.0 | 776 |
| direction | Republican for president, Democratic for House | 1972 | 25.0 | 22.6 | 27.3 | 1,293 |
| direction | Republican for president, Democratic for House | 1976 | 15.5 | 13.3 | 17.7 | 1,049 |
| direction | Republican for president, Democratic for House | 1980 | 19.8 | 17.0 | 22.6 | 762 |
| direction | Republican for president, Democratic for House | 1984 | 19.8 | 17.5 | 22.1 | 1,142 |
| direction | Republican for president, Democratic for House | 1988 | 18.3 | 15.9 | 20.6 | 1,030 |
| direction | Republican for president, Democratic for House | 1992 | 12.2 | 10.3 | 14.2 | 1,126 |
| direction | Republican for president, Democratic for House | 1996 | 4.3 | 2.8 | 5.7 | 926 |
| direction | Republican for president, Democratic for House | 2000 | 8.5 | 6.5 | 10.5 | 882 |
| direction | Republican for president, Democratic for House | 2004 | 9.6 | 7.2 | 12.0 | 701 |
| direction | Republican for president, Democratic for House | 2008 | 7.9 | 6.0 | 9.8 | 1,222 |
| direction | Republican for president, Democratic for House | 2012 | 4.0 | 3.2 | 4.9 | 3,501 |
| direction | Republican for president, Democratic for House | 2016 | 6.5 | 5.2 | 7.8 | 2,138 |
| direction | Republican for president, Democratic for House | 2020 | 4.6 | 3.8 | 5.4 | 5,167 |
| direction | Republican for president, Democratic for House | 2024 | 1.7 | 1.1 | 2.3 | 3,515 |
| direction | Democratic for president, Republican for House | 1952 | 2.3 | 1.4 | 3.2 | 1,009 |
| direction | Democratic for president, Republican for House | 1956 | 2.1 | 1.3 | 2.9 | 1,151 |
| direction | Democratic for president, Republican for House | 1960 | 4.2 | 2.5 | 5.9 | 766 |
| direction | Democratic for president, Republican for House | 1964 | 8.7 | 6.9 | 10.5 | 947 |
| direction | Democratic for president, Republican for House | 1968 | 7.0 | 5.2 | 8.8 | 776 |
| direction | Democratic for president, Republican for House | 1972 | 4.6 | 3.4 | 5.7 | 1,293 |
| direction | Democratic for president, Republican for House | 1976 | 9.3 | 7.5 | 11.0 | 1,049 |
| direction | Democratic for president, Republican for House | 1980 | 7.9 | 6.0 | 9.8 | 762 |
| direction | Democratic for president, Republican for House | 1984 | 5.6 | 4.3 | 6.9 | 1,142 |
| direction | Democratic for president, Republican for House | 1988 | 7.1 | 5.5 | 8.7 | 1,030 |
| direction | Democratic for president, Republican for House | 1992 | 10.1 | 8.3 | 11.9 | 1,126 |
| direction | Democratic for president, Republican for House | 1996 | 13.4 | 10.9 | 15.8 | 926 |
| direction | Democratic for president, Republican for House | 2000 | 9.8 | 7.7 | 12.0 | 882 |
| direction | Democratic for president, Republican for House | 2004 | 7.2 | 5.1 | 9.3 | 701 |
| direction | Democratic for president, Republican for House | 2008 | 8.9 | 6.9 | 10.8 | 1,222 |
| direction | Democratic for president, Republican for House | 2012 | 5.8 | 4.7 | 6.8 | 3,501 |
| direction | Democratic for president, Republican for House | 2016 | 8.8 | 7.3 | 10.2 | 2,138 |
| direction | Democratic for president, Republican for House | 2020 | 6.8 | 5.8 | 7.8 | 5,167 |
| direction | Democratic for president, Republican for House | 2024 | 3.0 | 2.2 | 3.8 | 3,515 |
| net | House Democratic share minus presidential Democratic share | 1952 | 8.0 | 5.9 | 10.2 | 1,009 |
| net | House Democratic share minus presidential Democratic share | 1956 | 11.4 | 9.2 | 13.6 | 1,151 |
| net | House Democratic share minus presidential Democratic share | 1960 | 5.6 | 2.5 | 8.6 | 766 |
| net | House Democratic share minus presidential Democratic share | 1964 | −2.2 | −4.7 | 0.3 | 947 |
| net | House Democratic share minus presidential Democratic share | 1968 | 3.9 | 0.9 | 6.8 | 776 |
| net | House Democratic share minus presidential Democratic share | 1972 | 20.4 | 17.7 | 23.2 | 1,293 |
| net | House Democratic share minus presidential Democratic share | 1976 | 6.3 | 3.2 | 9.3 | 1,049 |
| net | House Democratic share minus presidential Democratic share | 1980 | 11.9 | 8.3 | 15.6 | 762 |
| net | House Democratic share minus presidential Democratic share | 1984 | 14.2 | 11.4 | 17.0 | 1,142 |
| net | House Democratic share minus presidential Democratic share | 1988 | 11.2 | 8.2 | 14.2 | 1,030 |
| net | House Democratic share minus presidential Democratic share | 1992 | 2.1 | −0.6 | 4.9 | 1,126 |
| net | House Democratic share minus presidential Democratic share | 1996 | −9.1 | −12.0 | −6.1 | 926 |
| net | House Democratic share minus presidential Democratic share | 2000 | −1.4 | −4.5 | 1.8 | 882 |
| net | House Democratic share minus presidential Democratic share | 2004 | 2.4 | −0.9 | 5.7 | 701 |
| net | House Democratic share minus presidential Democratic share | 2008 | −1.0 | −3.8 | 1.9 | 1,222 |
| net | House Democratic share minus presidential Democratic share | 2012 | −1.7 | −3.1 | −0.3 | 3,501 |
| net | House Democratic share minus presidential Democratic share | 2016 | −2.3 | −4.3 | −0.2 | 2,138 |
| net | House Democratic share minus presidential Democratic share | 2020 | −2.2 | −3.5 | −0.9 | 5,167 |
| net | House Democratic share minus presidential Democratic share | 2024 | −1.3 | −2.3 | −0.2 | 3,515 |

Views: Which kind of split (panel = direction); Net effect on the House vote (panel = net).

Note: Net effect, second view: the weighted mean of the House Democratic vote minus the presidential Democratic vote among the same voters, in points. Zero means the two Democratic shares are equal even if many voters split in each direction.

Source: ANES Cumulative Data File, 1952-2024; weighted (post-election weight where the file has one, VCF0009z elsewhere)

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/split_direction.json

### Table 4. Counties whose presidential and House winners differed fell from 31.0% of counties in 1992 to 2.8% in 2024

Share of counties, and of presidential two-party votes, where the Democratic and Republican presidential winner differs from the House winner, counties with a contested House race, 1992 to 2024

| Office | View | Measure | Election | Share (%) | Counties | Counties in sample |
| --- | --- | --- | ---: | ---: | ---: | ---: |
| House | share | Counties | 1992 | 31.0 | n/a | 2,735 |
| House | share | Presidential votes | 1992 | 27.9 | n/a | 2,735 |
| House | share | Counties, uncontested races included | 1992 | 30.6 | n/a | 2,843 |
| House | direction | Republican for president, Democratic down the ballot | 1992 | n/a | 573 | 2,735 |
| House | direction | Democratic for president, Republican down the ballot | 1992 | n/a | 276 | 2,735 |
| House | share | Counties | 1996 | 25.6 | n/a | 2,703 |
| House | share | Presidential votes | 1996 | 24.8 | n/a | 2,703 |
| House | share | Counties, uncontested races included | 1996 | 25.4 | n/a | 2,769 |
| House | direction | Republican for president, Democratic down the ballot | 1996 | n/a | 226 | 2,703 |
| House | direction | Democratic for president, Republican down the ballot | 1996 | n/a | 466 | 2,703 |
| House | share | Counties | 2000 | 27.0 | n/a | 2,555 |
| House | share | Presidential votes | 2000 | 21.8 | n/a | 2,555 |
| House | share | Counties, uncontested races included | 2000 | 26.2 | n/a | 2,918 |
| House | direction | Republican for president, Democratic down the ballot | 2000 | n/a | 521 | 2,555 |
| House | direction | Democratic for president, Republican down the ballot | 2000 | n/a | 170 | 2,555 |
| House | share | Counties | 2004 | 25.5 | n/a | 2,479 |
| House | share | Presidential votes | 2004 | 21.5 | n/a | 2,479 |
| House | share | Counties, uncontested races included | 2004 | 23.3 | n/a | 2,848 |
| House | direction | Republican for president, Democratic down the ballot | 2004 | n/a | 516 | 2,479 |
| House | direction | Democratic for president, Republican down the ballot | 2004 | n/a | 115 | 2,479 |
| House | share | Counties | 2008 | 26.6 | n/a | 2,661 |
| House | share | Presidential votes | 2008 | 18.3 | n/a | 2,661 |
| House | share | Counties, uncontested races included | 2008 | 26.8 | n/a | 2,925 |
| House | direction | Republican for president, Democratic down the ballot | 2008 | n/a | 560 | 2,661 |
| House | direction | Democratic for president, Republican down the ballot | 2008 | n/a | 148 | 2,661 |
| House | share | Counties | 2012 | 9.7 | n/a | 2,609 |
| House | share | Presidential votes | 2012 | 10.9 | n/a | 2,609 |
| House | share | Counties, uncontested races included | 2012 | 9.2 | n/a | 2,857 |
| House | direction | Republican for president, Democratic down the ballot | 2012 | n/a | 162 | 2,609 |
| House | direction | Democratic for president, Republican down the ballot | 2012 | n/a | 90 | 2,609 |
| House | share | Counties | 2016 | 7.7 | n/a | 2,427 |
| House | share | Presidential votes | 2016 | 8.7 | n/a | 2,427 |
| House | share | Counties, uncontested races included | 2016 | 7.1 | n/a | 2,921 |
| House | direction | Republican for president, Democratic down the ballot | 2016 | n/a | 131 | 2,427 |
| House | direction | Democratic for president, Republican down the ballot | 2016 | n/a | 57 | 2,427 |
| House | share | Counties | 2020 | 3.0 | n/a | 2,884 |
| House | share | Presidential votes | 2020 | 5.1 | n/a | 2,884 |
| House | share | Counties, uncontested races included | 2020 | 3.4 | n/a | 3,084 |
| House | direction | Republican for president, Democratic down the ballot | 2020 | n/a | 40 | 2,884 |
| House | direction | Democratic for president, Republican down the ballot | 2020 | n/a | 47 | 2,884 |
| House | share | Counties | 2024 | 2.8 | n/a | 2,695 |
| House | share | Presidential votes | 2024 | 5.5 | n/a | 2,695 |
| House | share | Counties, uncontested races included | 2024 | 2.7 | n/a | 3,017 |
| House | direction | Republican for president, Democratic down the ballot | 2024 | n/a | 49 | 2,695 |
| House | direction | Democratic for president, Republican down the ballot | 2024 | n/a | 27 | 2,695 |
| Senate | share | Counties | 1992 | 30.9 | n/a | 1,824 |
| Senate | share | Presidential votes | 1992 | 29.3 | n/a | 1,824 |
| Senate | share | Counties, uncontested races included | 1992 | 30.9 | n/a | 1,824 |
| Senate | direction | Republican for president, Democratic down the ballot | 1992 | n/a | 271 | 1,824 |
| Senate | direction | Democratic for president, Republican down the ballot | 1992 | n/a | 293 | 1,824 |
| Senate | share | Counties | 1996 | 20.2 | n/a | 2,288 |
| Senate | share | Presidential votes | 1996 | 18.1 | n/a | 2,288 |
| Senate | share | Counties, uncontested races included | 1996 | 20.2 | n/a | 2,288 |
| Senate | direction | Republican for president, Democratic down the ballot | 1996 | n/a | 94 | 2,288 |
| Senate | direction | Democratic for president, Republican down the ballot | 1996 | n/a | 369 | 2,288 |
| Senate | share | Counties | 2000 | 21.1 | n/a | 1,858 |
| Senate | share | Presidential votes | 2000 | 22.9 | n/a | 1,858 |
| Senate | share | Counties, uncontested races included | 2000 | 21.1 | n/a | 1,858 |
| Senate | direction | Republican for president, Democratic down the ballot | 2000 | n/a | 256 | 1,858 |
| Senate | direction | Democratic for president, Republican down the ballot | 2000 | n/a | 136 | 1,858 |
| Senate | share | Counties | 2004 | 29.6 | n/a | 2,006 |
| Senate | share | Presidential votes | 2004 | 26.6 | n/a | 2,006 |
| Senate | share | Counties, uncontested races included | 2004 | 29.0 | n/a | 2,050 |
| Senate | direction | Republican for president, Democratic down the ballot | 2004 | n/a | 506 | 2,006 |
| Senate | direction | Democratic for president, Republican down the ballot | 2004 | n/a | 88 | 2,006 |
| Senate | share | Counties | 2008 | 24.4 | n/a | 2,055 |
| Senate | share | Presidential votes | 2008 | 15.2 | n/a | 2,055 |
| Senate | share | Counties, uncontested races included | 2008 | 24.4 | n/a | 2,055 |
| Senate | direction | Republican for president, Democratic down the ballot | 2008 | n/a | 436 | 2,055 |
| Senate | direction | Democratic for president, Republican down the ballot | 2008 | n/a | 65 | 2,055 |
| Senate | share | Counties | 2012 | 18.2 | n/a | 1,843 |
| Senate | share | Presidential votes | 2012 | 13.4 | n/a | 1,843 |
| Senate | share | Counties, uncontested races included | 2012 | 18.2 | n/a | 1,843 |
| Senate | direction | Republican for president, Democratic down the ballot | 2012 | n/a | 315 | 1,843 |
| Senate | direction | Democratic for president, Republican down the ballot | 2012 | n/a | 20 | 1,843 |
| Senate | share | Counties | 2016 | 6.2 | n/a | 1,989 |
| Senate | share | Presidential votes | 2016 | 10.7 | n/a | 1,989 |
| Senate | share | Counties, uncontested races included | 2016 | 7.2 | n/a | 2,045 |
| Senate | direction | Republican for president, Democratic down the ballot | 2016 | n/a | 84 | 1,989 |
| Senate | direction | Democratic for president, Republican down the ballot | 2016 | n/a | 40 | 1,989 |
| Senate | share | Counties | 2020 | 1.9 | n/a | 2,212 |
| Senate | share | Presidential votes | 2020 | 3.6 | n/a | 2,212 |
| Senate | share | Counties, uncontested races included | 2020 | 1.9 | n/a | 2,212 |
| Senate | direction | Republican for president, Democratic down the ballot | 2020 | n/a | 21 | 2,212 |
| Senate | direction | Democratic for president, Republican down the ballot | 2020 | n/a | 22 | 2,212 |
| Senate | share | Counties | 2024 | 3.0 | n/a | 1,749 |
| Senate | share | Presidential votes | 2024 | 8.7 | n/a | 1,749 |
| Senate | share | Counties, uncontested races included | 2024 | 3.0 | n/a | 1,749 |
| Senate | direction | Republican for president, Democratic down the ballot | 2024 | n/a | 45 | 1,749 |
| Senate | direction | Democratic for president, Republican down the ballot | 2024 | n/a | 8 | 1,749 |

Views: House (office = House, panel = share); Senate (office = Senate, panel = share); House, which kind (office = House, panel = direction); Senate, which kind (office = Senate, panel = direction).

Note: Full counts of votes, so the county series have no sampling interval.

Note: A winner is the party with more Democratic or Republican votes; third-party votes are left out, as in the two-party margin. A county is in the House sample when every district part of it was a contested race (both major parties on the ballot, together at least 80% of the votes). Jackson County, Missouri, is left out from 2004 to 2024 because the file omits the part of the county in Kansas City.

Source: County returns for President, U.S. House and U.S. Senate, 1992-2024 (Heideman 2026, with MIT Election Data and Science Lab presidential returns); full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/county_winners.json

### Table 5. Counties with different presidential and House winners were spread across regions in 1992, 32.5% of the South's counties and 29.9% of the other regions' counties

Counties by the party that won the presidential vote and the party that won the House vote, counties in contested House races, each presidential election from 1992 to 2024

No inline rows: the values of Table 5 are in https://vishalsingh.org/politics/data/down-the-ballot/divided_counties.json.

Views: House; Senate.

Note: Full counts of votes, so the county series have no sampling interval.

Note: Only counties in the main sample are colored: contested races in every district part, totals screen passed. Counties in uncontested races, in states without a Senate race (Senate view), counties with no usable returns and Jackson County, Missouri, from 2004 to 2024 (the file omits the part in Kansas City) draw as no data. Alaska and Hawaii are not in the county file. The South is the Census Bureau's South region.

Source: County returns for President, U.S. House and U.S. Senate, 1992-2024 (Heideman 2026, with MIT Election Data and Science Lab presidential returns); full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/county_map.json

### Table 6. The correlation between county presidential and House margins rose from +0.65 in 1992 to +0.99 in 2024

Vote-weighted correlation across counties between the Democratic minus Republican margin for president and for the House (or Senate), counties in contested races, 1992 to 2024; 95% intervals

| Office | Measure | Election | Estimate | Lower | Upper | Counties |
| --- | --- | ---: | ---: | ---: | ---: | ---: |
| House | correlation | 1992 | 0.65 | 0.56 | 0.72 | 2,735 |
| House | gap | 1992 | 16.36 | 14.55 | 18.69 | 2,735 |
| House | correlation | 1996 | 0.79 | 0.73 | 0.84 | 2,703 |
| House | gap | 1996 | 16.53 | 14.96 | 18.33 | 2,703 |
| House | correlation | 2000 | 0.74 | 0.66 | 0.80 | 2,555 |
| House | gap | 2000 | 17.98 | 16.05 | 19.89 | 2,555 |
| House | correlation | 2004 | 0.78 | 0.69 | 0.84 | 2,479 |
| House | gap | 2004 | 15.62 | 13.82 | 17.68 | 2,479 |
| House | correlation | 2008 | 0.82 | 0.76 | 0.86 | 2,661 |
| House | gap | 2008 | 13.49 | 12.08 | 15.24 | 2,661 |
| House | correlation | 2012 | 0.95 | 0.93 | 0.96 | 2,609 |
| House | gap | 2012 | 7.63 | 6.79 | 8.53 | 2,609 |
| House | correlation | 2016 | 0.93 | 0.89 | 0.96 | 2,427 |
| House | gap | 2016 | 8.73 | 7.58 | 10.01 | 2,427 |
| House | correlation | 2020 | 0.99 | 0.98 | 0.99 | 2,884 |
| House | gap | 2020 | 4.32 | 3.77 | 4.91 | 2,884 |
| House | correlation | 2024 | 0.99 | 0.99 | 0.99 | 2,695 |
| House | gap | 2024 | 3.70 | 3.24 | 4.22 | 2,695 |
| Senate | correlation | 1992 | 0.63 | 0.47 | 0.79 | 1,824 |
| Senate | gap | 1992 | 15.93 | 12.12 | 21.09 | 1,824 |
| Senate | correlation | 1996 | 0.84 | 0.76 | 0.91 | 2,288 |
| Senate | gap | 1996 | 10.89 | 7.78 | 14.96 | 2,288 |
| Senate | correlation | 2000 | 0.82 | 0.72 | 0.88 | 1,858 |
| Senate | gap | 2000 | 13.89 | 10.78 | 18.45 | 1,858 |
| Senate | correlation | 2004 | 0.78 | 0.67 | 0.87 | 2,006 |
| Senate | gap | 2004 | 18.05 | 13.51 | 23.38 | 2,006 |
| Senate | correlation | 2008 | 0.87 | 0.80 | 0.92 | 2,055 |
| Senate | gap | 2008 | 12.06 | 8.82 | 15.77 | 2,055 |
| Senate | correlation | 2012 | 0.93 | 0.88 | 0.97 | 1,843 |
| Senate | gap | 2012 | 8.71 | 5.66 | 12.50 | 1,843 |
| Senate | correlation | 2016 | 0.93 | 0.91 | 0.96 | 1,989 |
| Senate | gap | 2016 | 10.11 | 7.72 | 13.04 | 1,989 |
| Senate | correlation | 2020 | 0.99 | 0.98 | 0.99 | 2,212 |
| Senate | gap | 2020 | 3.93 | 3.24 | 4.90 | 2,212 |
| Senate | correlation | 2024 | 0.98 | 0.97 | 0.99 | 1,749 |
| Senate | gap | 2024 | 4.57 | 3.44 | 6.04 | 1,749 |

Views: Correlation (measure = correlation); Average gap in points (measure = gap).

Note: County returns are full counts. The intervals show how much the correlation depends on which states are in the sample: whole states are resampled in a bootstrap, and the methods note gives the replicates and seed.

Note: The gap view plots the vote-weighted mean absolute difference between the down-ballot margin and the presidential margin, in points of margin.

Source: County returns for President, U.S. House and U.S. Senate, 1992-2024 (Heideman 2026, with MIT Election Data and Science Lab presidential returns); full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/margin_tracking.json

### Table 7. A shift shared by the counties of one district or state accounts for most of the gap between presidential and down-ballot margins

Vote-weighted root mean square of the down-ballot margin minus the presidential margin, in points of margin, and the part that varies among counties inside one district (House) or state (Senate), 1992 to 2024

| Series | Election | Root mean square (points) | Counties |
| --- | ---: | ---: | ---: |
| House, whole gap | 1992 | 27.0 | 2,348 |
| House, variation inside a district | 1992 | 9.1 | 2,348 |
| House, whole gap | 1996 | 23.4 | 2,329 |
| House, variation inside a district | 1996 | 7.3 | 2,329 |
| House, whole gap | 2000 | 28.4 | 2,190 |
| House, variation inside a district | 2000 | 7.1 | 2,190 |
| House, whole gap | 2004 | 27.8 | 2,078 |
| House, variation inside a district | 2004 | 7.4 | 2,078 |
| House, whole gap | 2008 | 24.8 | 2,280 |
| House, variation inside a district | 2008 | 7.4 | 2,280 |
| House, whole gap | 2012 | 12.5 | 2,229 |
| House, variation inside a district | 2012 | 5.0 | 2,229 |
| House, whole gap | 2016 | 14.3 | 2,037 |
| House, variation inside a district | 2016 | 6.0 | 2,037 |
| House, whole gap | 2020 | 6.3 | 2,445 |
| House, variation inside a district | 2020 | 2.6 | 2,445 |
| House, whole gap | 2024 | 5.5 | 2,277 |
| House, variation inside a district | 2024 | 2.3 | 2,277 |
| Senate, whole gap | 1992 | 20.5 | 1,823 |
| Senate, variation inside a state | 1992 | 8.0 | 1,823 |
| Senate, whole gap | 1996 | 15.2 | 2,288 |
| Senate, variation inside a state | 1996 | 5.7 | 2,288 |
| Senate, whole gap | 2000 | 18.5 | 1,858 |
| Senate, variation inside a state | 2000 | 6.0 | 1,858 |
| Senate, whole gap | 2004 | 22.7 | 2,006 |
| Senate, variation inside a state | 2004 | 6.9 | 2,006 |
| Senate, whole gap | 2008 | 16.0 | 2,055 |
| Senate, variation inside a state | 2008 | 6.6 | 2,055 |
| Senate, whole gap | 2012 | 12.6 | 1,843 |
| Senate, variation inside a state | 2012 | 4.5 | 1,843 |
| Senate, whole gap | 2016 | 13.4 | 1,989 |
| Senate, variation inside a state | 2016 | 8.0 | 1,989 |
| Senate, whole gap | 2020 | 5.5 | 2,212 |
| Senate, variation inside a state | 2020 | 3.0 | 2,212 |
| Senate, whole gap | 2024 | 6.1 | 1,749 |
| Senate, variation inside a state | 2024 | 2.5 | 1,749 |

Note: Full counts of votes, so the county series have no sampling interval.

Note: A root mean square is the square root of the vote-weighted mean of the squared gap, so large gaps count more than in an average of absolute gaps. Districts and states with one county in the sample are left out, and the part inside each unit is multiplied by n over n minus one for a unit of n counties, because a unit's own average absorbs part of its counties' deviations.

Source: County returns for President, U.S. House and U.S. Senate, 1992-2024 (Heideman 2026, with MIT Election Data and Science Lab presidential returns); full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/gap_components.json

### Table 8. Between 1992 and 2024 the share of ANES voters who split their ticket fell by 17.7 points and the share of divided counties by 28.2 points

Share of ANES voters whose presidential and House votes were for different parties (95% intervals), and share of counties in contested House races with different presidential and House winners, 1992 to 2024

| Measure | Election | Share (%) | Respondents or counties |
| --- | ---: | ---: | ---: |
| Voters who split their ticket (ANES) | 1992 | 22.3 | 1,126 |
| Counties with different winners | 1992 | 31.0 | 2,735 |
| Voters who split their ticket (ANES) | 1996 | 17.7 | 926 |
| Counties with different winners | 1996 | 25.6 | 2,703 |
| Voters who split their ticket (ANES) | 2000 | 18.3 | 882 |
| Counties with different winners | 2000 | 27.0 | 2,555 |
| Voters who split their ticket (ANES) | 2004 | 16.8 | 701 |
| Counties with different winners | 2004 | 25.5 | 2,479 |
| Voters who split their ticket (ANES) | 2008 | 16.7 | 1,222 |
| Counties with different winners | 2008 | 26.6 | 2,661 |
| Voters who split their ticket (ANES) | 2012 | 9.8 | 3,501 |
| Counties with different winners | 2012 | 9.7 | 2,609 |
| Voters who split their ticket (ANES) | 2016 | 15.3 | 2,138 |
| Counties with different winners | 2016 | 7.7 | 2,427 |
| Voters who split their ticket (ANES) | 2020 | 11.4 | 5,167 |
| Counties with different winners | 2020 | 3.0 | 2,884 |
| Voters who split their ticket (ANES) | 2024 | 4.7 | 3,515 |
| Counties with different winners | 2024 | 2.8 | 2,695 |

Note: The voter line is the ANES rate of self-reported splitting among respondents with a major-party vote for president and the House. The county line is a share of counties and has no sampling interval.

Source: ANES Cumulative Data File, 1992-2024, weighted (post-election weight where the file has one, VCF0009z elsewhere); county returns for President and U.S. House, 1992-2024, full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/both_measures.json

### Table 9. The main House sample holds between 71% and 84% of the presidential votes of the contiguous states and the main Senate sample between 49% and 74%

Counties, share of the 48 contiguous states' presidential two-party votes, and share of divided counties in the main House and Senate samples, by election

| Election | Counties with presidential votes | House sample, counties | House sample, share of presidential votes (%) | House sample, divided counties (%) | Senate class | Senate sample, counties | Senate sample, share of presidential votes (%) | Senate sample, divided counties (%) |
| ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: | ---: |
| 1992 | 3,109 | 2,735 | 77 | 31.0 | 3 | 1,824 | 68 | 30.9 |
| 1996 | 3,108 | 2,703 | 83 | 25.6 | 2 | 2,288 | 53 | 20.2 |
| 2000 | 3,107 | 2,555 | 71 | 27.0 | 1 | 1,858 | 74 | 21.1 |
| 2004 | 3,108 | 2,479 | 71 | 25.5 | 3 | 2,006 | 72 | 29.6 |
| 2008 | 3,108 | 2,661 | 77 | 26.6 | 2 | 2,055 | 49 | 24.4 |
| 2012 | 3,108 | 2,609 | 79 | 9.7 | 1 | 1,843 | 73 | 18.2 |
| 2016 | 3,107 | 2,427 | 71 | 7.7 | 3 | 1,989 | 62 | 6.2 |
| 2020 | 3,107 | 2,884 | 84 | 3.0 | 2 | 2,212 | 51 | 1.9 |
| 2024 | 3,107 | 2,695 | 81 | 2.8 | 1 | 1,749 | 73 | 3.0 |

Note: Full counts of votes, so the county series have no sampling interval.

Note: A Senate class is the set of seats that come up together every six years. In presidential years the three classes alternate, so a class comes up in 1992, 2004 and 2016 (class 3), 1996, 2008 and 2020 (class 2) and 2000, 2012 and 2024 (class 1). The Senate sample is the states with a contested regular race.

Source: County returns for President, U.S. House and U.S. Senate, 1992-2024 (Heideman 2026, with MIT Election Data and Science Lab presidential returns); full counts, unweighted

Data: https://vishalsingh.org/politics/report/down-the-ballot/figures/coverage.json

## All estimates

Every fact in facts.json (191), sorted by id.

| Fact id | Value | Unit | Estimand | Population | Period | Interval | n | Weights | Source | Note |
| --- | ---: | --- | --- | --- | --- | --- | ---: | --- | --- | --- |
| anes_dem_2024 | 55.3% | percent of the two-party presidential vote | weighted Democratic share of the major-party presidential vote | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI 53.0% to 57.7% | 3,515 | weight_postelection (VCF9999) | ANES Cumulative Data File |   |
| both_chg_anes | 17.7 | percentage points | 1992 share who split minus 2024 share | respondents who reported a major-party presidential vote and a major-party House vote | 1992 to 2024 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| cert_dem_2024 | 49.2% | percent of the two-party presidential vote | certified Democratic share of the Democratic and Republican presidential votes | all states and the District of Columbia | 2024 |   |   | none (full counts) | State presidential returns |   |
| drh_1972 | 4.6% | percent of voters | weighted share who voted Democratic for president and Republican for the House | respondents who reported a major-party presidential vote and a major-party House vote | 1972 | 95% CI 3.4% to 5.7% | 1,293 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drh_1996 | 13.4% | percent of voters | weighted share who voted Democratic for president and Republican for the House | respondents who reported a major-party presidential vote and a major-party House vote | 1996 | 95% CI 10.9% to 15.8% | 926 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drh_2020 | 6.8% | percent of voters | weighted share who voted Democratic for president and Republican for the House | respondents who reported a major-party presidential vote and a major-party House vote | 2020 | 95% CI 5.8% to 7.8% | 5,167 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drh_2024 | 3.0% | percent of voters | weighted share who voted Democratic for president and Republican for the House | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI 2.2% to 3.8% | 3,515 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drop_h_1972_2024 | 24.9 | percentage points | decrease in the weighted share who split, 1972 minus 2024 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 1972 to 2024 | 95% CI 22.2 to 27.5 | 4,808 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drop_h_1992_2024 | 17.7 | percentage points | decrease in the weighted share who split, 1992 minus 2024 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 1992 to 2024 | 95% CI 15.0 to 20.3 | 4,641 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drop_h_2008_2012 | 6.9 | percentage points | decrease in the weighted share who split, 2008 minus 2012 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2008 to 2012 | 95% CI 4.0 to 9.8 | 4,723 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| drop_h_2020_2024 | 6.7 | percentage points | decrease in the weighted share who split, 2020 minus 2024 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2020 to 2024 | 95% CI 5.1 to 8.2 | 8,682 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| ftf_chg_2012_2016 | −0.9 | percentage points | difference in weighted shares who split, 2016 minus 2012 (separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2012 to 2016, in-person respondents, president and House | 95% CI −4.8 to 3.1 | 1,684 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| ftf_drop_2008_2012 | 5.7 | percentage points | decrease in the weighted share who split among in-person respondents, 2008 minus 2012 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2008 to 2012, in-person respondents | 95% CI 2.1 to 9.4 | 2,287 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| ftf_drop_2016_2024 | 4.9 | percentage points | decrease in the weighted share who split, 2016 minus 2024 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2016 to 2024, in-person respondents | 95% CI 1.0 to 8.8 | 1,198 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| house_all_div_1992 | 30.6% | percent of counties | share of divided counties, all returns that pass rules 1 to 3 | counties with House returns, uncontested races included | 1992 |   | 2,843 | none (full counts) | County election returns |   |
| house_all_div_2024 | 2.7% | percent of counties | share of divided counties, all returns that pass rules 1 to 3 | counties with House returns, uncontested races included | 2024 |   | 3,017 | none (full counts) | County election returns |   |
| house_between_1992 | 89% | percent of the mean square | share of the vote-weighted mean square of the gap that is the district mean gap, corrected by n/(n-1) | counties wholly inside one contested House district, in districts with at least two such counties | 1992 |   | 2,348 | none (full counts) | County election returns |   |
| house_between_2024 | 83% | percent of the mean square | share of the vote-weighted mean square of the gap that is the district mean gap, corrected by n/(n-1) | counties wholly inside one contested House district, in districts with at least two such counties | 2024 |   | 2,277 | none (full counts) | County election returns |   |
| house_between_hi | 94% | percent of the mean square | highest yearly corrected share of the mean square of the gap that is the district mean gap | counties wholly inside one contested House district, in districts with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_between_lo | 82% | percent of the mean square | lowest yearly corrected share of the mean square of the gap that is the district mean gap | counties wholly inside one contested House district, in districts with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_between_raw_hi | 94% | percent of the mean square | highest yearly share of the mean square that is the district mean gap, without the n/(n-1) correction | counties wholly inside one contested House district, in districts with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_between_raw_lo | 84% | percent of the mean square | lowest yearly share of the mean square that is the district mean gap, without the n/(n-1) correction | counties wholly inside one contested House district, in districts with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_cov_2024 | 81% | percent of presidential two-party votes | share of the presidential two-party votes of the 48 contiguous states cast in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   |   | none (full counts) | County election returns |   |
| house_cov_hi | 84% | percent of presidential two-party votes | highest yearly share of the presidential two-party votes of the 48 contiguous states cast in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_cov_lo | 71% | percent of presidential two-party votes | lowest yearly share of the presidential two-party votes of the 48 contiguous states cast in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_dem_rep_1992 | 276 | counties | count of counties won by the Democrat for president and the Republican for the House | counties in the 48 contiguous states with a contested House race in every district part | 1992 |   |   | none (full counts) | County election returns |   |
| house_dem_rep_1996 | 466 | counties | count of counties won by the Democrat for president and the Republican for the House | counties in the 48 contiguous states with a contested House race in every district part | 1996 |   |   | none (full counts) | County election returns |   |
| house_dem_rep_2020 | 47 | counties | count of counties won by the Democrat for president and the Republican for the House | counties in the 48 contiguous states with a contested House race in every district part | 2020 |   |   | none (full counts) | County election returns |   |
| house_dem_rep_2024 | 27 | counties | count of counties won by the Democrat for president and the Republican for the House | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   |   | none (full counts) | County election returns |   |
| house_div_1992 | 31.0% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 1992 |   | 2,735 | none (full counts) | County election returns |   |
| house_div_2008 | 26.6% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2008 |   | 2,661 | none (full counts) | County election returns |   |
| house_div_2012 | 9.7% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2012 |   | 2,609 | none (full counts) | County election returns |   |
| house_div_2016 | 7.7% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2016 |   | 2,427 | none (full counts) | County election returns |   |
| house_div_2020 | 3.0% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2020 |   | 2,884 | none (full counts) | County election returns |   |
| house_div_2024 | 2.8% | percent of counties | share of counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   | 2,695 | none (full counts) | County election returns |   |
| house_early_hi | 31.0% | percent of counties | highest yearly share of divided counties, House | counties in the 48 contiguous states with a contested House race in every district part | 1992-2008 |   |   | none (full counts) | County election returns |   |
| house_early_lo | 25.5% | percent of counties | lowest yearly share of divided counties, House | counties in the 48 contiguous states with a contested House race in every district part | 1992-2008 |   |   | none (full counts) | County election returns |   |
| house_fall_0812 | 16.9 | percentage points | 2008 share of divided counties minus 2012 share, House | counties in the 48 contiguous states with a contested House race in every district part | 2008 to 2012 |   |   | none (full counts) | County election returns |   |
| house_fall_1992_2024 | 28.2 | percentage points | 1992 share of divided counties minus 2024 share, House | counties in the 48 contiguous states with a contested House race in every district part | 1992 to 2024 |   |   | none (full counts) | County election returns |   |
| house_late_hi | 9.7% | percent of counties | highest yearly share of divided counties from 2012 on, House | counties in the 48 contiguous states with a contested House race in every district part | 2012-2024 |   |   | none (full counts) | County election returns |   |
| house_mad_1992 | 16.4 | points of margin | vote-weighted mean absolute difference between the House margin and the presidential margin | counties in the 48 contiguous states with a contested House race in every district part | 1992 | 95% CI 14.5 to 18.7 | 2,735 | presidential two-party votes in the county | County election returns |   |
| house_mad_2024 | 3.7 | points of margin | vote-weighted mean absolute difference between the House margin and the presidential margin | counties in the 48 contiguous states with a contested House race in every district part | 2024 | 95% CI 3.2 to 4.2 | 2,695 | presidential two-party votes in the county | County election returns |   |
| house_r_1992 | +0.65 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 1992 | 95% CI 0.56 to 0.72 | 2,735 | presidential two-party votes in the county | County election returns |   |
| house_r_2008 | +0.82 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 2008 | 95% CI 0.76 to 0.86 | 2,661 | presidential two-party votes in the county | County election returns |   |
| house_r_2012 | +0.95 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 2012 | 95% CI 0.93 to 0.96 | 2,609 | presidential two-party votes in the county | County election returns |   |
| house_r_2020 | +0.99 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 2020 | 95% CI 0.98 to 0.99 | 2,884 | presidential two-party votes in the county | County election returns |   |
| house_r_2024 | +0.99 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 2024 | 95% CI 0.99 to 0.99 | 2,695 | presidential two-party votes in the county | County election returns |   |
| house_rep_dem_1992 | 573 | counties | count of counties won by the Republican for president and the Democrat for the House | counties in the 48 contiguous states with a contested House race in every district part | 1992 |   |   | none (full counts) | County election returns |   |
| house_rep_dem_1996 | 226 | counties | count of counties won by the Republican for president and the Democrat for the House | counties in the 48 contiguous states with a contested House race in every district part | 1996 |   |   | none (full counts) | County election returns |   |
| house_rep_dem_2020 | 40 | counties | count of counties won by the Republican for president and the Democrat for the House | counties in the 48 contiguous states with a contested House race in every district part | 2020 |   |   | none (full counts) | County election returns |   |
| house_rep_dem_2024 | 49 | counties | count of counties won by the Republican for president and the Democrat for the House | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   |   | none (full counts) | County election returns |   |
| house_rest_1992 | 29.9% | percent of counties | share of counties that are divided, rest of the country | counties in the 48 contiguous states with a contested House race in every district part, outside the Census South region | 1992 |   | 1,528 | none (full counts) | County election returns |   |
| house_rest_2004 | 22.2% | percent of counties | share of counties that are divided, rest of the country | counties in the 48 contiguous states with a contested House race in every district part, outside the Census South region | 2004 |   | 1,494 | none (full counts) | County election returns |   |
| house_rest_2012 | 11.2% | percent of counties | share of counties that are divided, rest of the country | counties in the 48 contiguous states with a contested House race in every district part, outside the Census South region | 2012 |   | 1,480 | none (full counts) | County election returns |   |
| house_rest_2016 | 9.6% | percent of counties | share of counties that are divided, rest of the country | counties in the 48 contiguous states with a contested House race in every district part, outside the Census South region | 2016 |   | 1,424 | none (full counts) | County election returns |   |
| house_rest_2024 | 2.7% | percent of counties | share of counties that are divided, rest of the country | counties in the 48 contiguous states with a contested House race in every district part, outside the Census South region | 2024 |   | 1,575 | none (full counts) | County election returns |   |
| house_rms_1992 | 27.0 | points of margin | vote-weighted root mean square of the House margin minus the presidential margin | counties wholly inside one contested House district, in districts with at least two such counties | 1992 |   | 2,348 | none (full counts) | County election returns |   |
| house_rms_2024 | 5.5 | points of margin | vote-weighted root mean square of the House margin minus the presidential margin | counties wholly inside one contested House district, in districts with at least two such counties | 2024 |   | 2,277 | none (full counts) | County election returns |   |
| house_rms_in_1992 | 9.1 | points of margin | vote-weighted root mean square of the gap after subtracting each district mean gap, corrected by n/(n-1) | counties wholly inside one contested House district, in districts with at least two such counties | 1992 |   | 2,348 | none (full counts) | County election returns |   |
| house_rms_in_2024 | 2.3 | points of margin | vote-weighted root mean square of the gap after subtracting each district mean gap, corrected by n/(n-1) | counties wholly inside one contested House district, in districts with at least two such counties | 2024 |   | 2,277 | none (full counts) | County election returns |   |
| house_ru_1992 | +0.58 | correlation coefficient, from -1 to +1 | county-equal correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 1992 | 95% CI 0.47 to 0.67 | 2,735 | none (each county counted once) | County election returns |   |
| house_ru_2024 | +0.98 | correlation coefficient, from -1 to +1 | county-equal correlation between the county presidential margin and the House margin | counties in the 48 contiguous states with a contested House race in every district part | 2024 | 95% CI 0.98 to 0.99 | 2,695 | none (each county counted once) | County election returns |   |
| house_senate_r | +0.94 | correlation coefficient, from -1 to +1 | correlation across the 19 studies between the yearly president and House share who split and the president and Senate share | ANES studies with both series | 1952-2024 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| house_sens_max | 2.1 | percentage points | largest yearly difference in the share of divided counties between the main sample and all returns, House | counties with House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_sens_year | 2004 | year | election with the largest difference between the main sample and all returns, House | counties with House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| house_south_1992 | 32.5% | percent of counties | share of counties that are divided, South | counties in the 48 contiguous states with a contested House race in every district part, Census South region | 1992 |   | 1,207 | none (full counts) | County election returns |   |
| house_south_2004 | 30.5% | percent of counties | share of counties that are divided, South | counties in the 48 contiguous states with a contested House race in every district part, Census South region | 2004 |   | 985 | none (full counts) | County election returns |   |
| house_south_2012 | 7.6% | percent of counties | share of counties that are divided, South | counties in the 48 contiguous states with a contested House race in every district part, Census South region | 2012 |   | 1,129 | none (full counts) | County election returns |   |
| house_south_2016 | 5.1% | percent of counties | share of counties that are divided, South | counties in the 48 contiguous states with a contested House race in every district part, Census South region | 2016 |   | 1,003 | none (full counts) | County election returns |   |
| house_south_2024 | 2.9% | percent of counties | share of counties that are divided, South | counties in the 48 contiguous states with a contested House race in every district part, Census South region | 2024 |   | 1,120 | none (full counts) | County election returns |   |
| house_votes_1992 | 27.9% | percent of presidential two-party votes | share of presidential two-party votes cast in counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 1992 |   | 2,735 | none (full counts) | County election returns |   |
| house_votes_2024 | 5.5% | percent of presidential two-party votes | share of presidential two-party votes cast in counties whose presidential winner differs from the House winner | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   | 2,695 | none (full counts) | County election returns |   |
| major_min | 80% | percent of votes in the race | least share of all votes that the two major-party candidates together must win for a race to count as a two-party race | county races | 1992-2024 |   |   | none (full counts) | County election returns |   |
| mid_hi | 18.3% | percent of voters | highest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1996-2008 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| mid_lo | 16.7% | percent of voters | lowest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1996-2008 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| mode_diff_2012 | −1.9 | percentage points | web minus in-person difference in the weighted share who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2012 | 95% CI −4.9 to 1.1 | 3,501 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| mode_diff_2016 | +7.2 | percentage points | web minus in-person difference in the weighted share who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2016 | 95% CI 3.4 to 10.9 | 2,138 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| mode_diff_2024 | −0.3 | percentage points | web minus in-person difference in the weighted share who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI −3.2 to 2.7 | 1,806 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| n_2024_other | 1,709 | respondents | count in neither mode group (panel and paper cases) | respondents who reported a major-party presidential vote and a major-party House vote | 2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_check_both | 25,637 | respondents | count of respondents whose rebuilt code is compared with VCF0709 | respondents with VCF0709 and both vote items | 1952-2020 |   |   | none (count) | ANES Cumulative Data File |   |
| n_check_only_vcf | 2 | respondents | count with VCF0709 but a missing presidential or House vote item | 1984 respondents with VCF0709 | 1984 |   |   | none (count) | ANES Cumulative Data File |   |
| n_check_years | 18 | studies | count of studies in which the rebuilt code is compared with VCF0709 | ANES studies with VCF0709 | 1952-2020 |   |   | none (count) | ANES Cumulative Data File |   |
| n_common | 19 | studies | count of studies in the correlation between the House and Senate series | ANES studies with both series | 1952-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_drh_larger | 7 | studies | count of studies in which the Democratic-president, Republican-House share exceeds the Republican-president, Democratic-House share (point estimates) | ANES studies from 1996 to 2024 | 1996-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_elections | 9 | elections | count of presidential elections compared | presidential elections in the county file | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_house | 29,103 | respondents | count of respondents with a post-election weight in the 19 studies | respondents who reported a major-party presidential vote and a major-party House vote | 1952-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_house_1992 | 2,735 | counties | count of counties in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 1992 |   |   | none (full counts) | County election returns |   |
| n_house_2024 | 2,695 | counties | count of counties in the main House sample | counties in the 48 contiguous states with a contested House race in every district part | 2024 |   |   | none (full counts) | County election returns |   |
| n_house_race_binds | 14 | races | count of House races that fail only the 80% condition | House races with candidates of both parties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_house_race_rule | 3,097 | county-years | count removed because the race was not a contested two-party race | county-years that pass rules 1 and 2, House | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_house_rd_larger | 7 | elections | count of elections in which counties with a Republican for president and a Democrat for the House outnumber the reverse | counties in the 48 contiguous states with a contested House race in every district part | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_house_returns | 27,567 | county-years | count of county-years with presidential votes and House returns | county-years with presidential votes and House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_house_screen | 687 | county-years | count removed by the totals screen | county-years with presidential votes and House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_indep_senate | 123 | county-years | count removed because an independent is coded as a major-party candidate (Maine and Vermont 2012, Nebraska 2024) | county-years with presidential votes and Senate returns | 2012 and 2024 |   |   | none (full counts) | County election returns |   |
| n_kc_years | 6 | elections | count of elections in which Jackson County is left out because the file omits the Kansas City part | Jackson County, Missouri | 2004-2024 |   |   | none (full counts) | County election returns |   |
| n_no_post_weight | 64 | respondents | count with both votes but no post-election weight in a study that has one | respondents who reported a major-party presidential vote and a major-party House vote | 2016, 2020 and 2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_post96 | 8 | studies | count of ANES studies from 1996 to 2024 | ANES studies from 1996 to 2024 | 1996-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_pres_counties_2024 | 3,107 | counties | count of counties with presidential two-party votes | counties in the 48 contiguous states with presidential votes | 2024 |   |   | none (full counts) | County election returns |   |
| n_rebuilt_2024 | 3,530 | respondents | count of respondents whose president-House code exists only in the rebuilt version | respondents who reported a major-party presidential vote and a major-party House vote | 2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_screen_ga_1992 | 158 | county-years | count removed by the totals screen | Georgia Senate 1992 | 1992 |   |   | none (full counts) | County election returns |   |
| n_screen_ga_2008 | 157 | county-years | count removed by the totals screen | Georgia Senate 2008 | 2008 |   |   | none (full counts) | County election returns |   |
| n_screen_ia_2012 | 99 | county-years | count removed by the totals screen | Iowa House 2012 | 2012 |   |   | none (full counts) | County election returns |   |
| n_screen_la_1992 | 61 | county-years | count removed by the totals screen | Louisiana Senate 1992 | 1992 |   |   | none (full counts) | County election returns |   |
| n_screen_other_house | 588 | county-years | count removed by the totals screen outside the Iowa 2012 file | county-years with presidential votes and House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_screen_other_house_c | 150 | county-years | count of those that would otherwise be in the main House sample | county-years with presidential votes and House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_screen_other_senate | 22 | county-years | count removed by the totals screen outside the three named Senate state-years | county-years with presidential votes and Senate returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate | 20,334 | respondents | count of respondents with a post-election weight in the 19 studies | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 1952-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| n_senate_race_binds | 1 | races | count of Senate races that fail only the 80% condition | Senate races with candidates of both parties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate_race_rule | 295 | county-years | count removed because the race was not a contested two-party race | county-years that pass rules 1 and 2, Senate | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate_rd_larger | 6 | elections | count of elections in which counties with a Republican for president and a Democrat for the Senate outnumber the reverse | counties in the 48 contiguous states with a contested Senate race | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate_returns | 18,645 | county-years | count of county-years with presidential votes and Senate returns | county-years with presidential votes and Senate returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate_screen | 398 | county-years | count removed by the totals screen | county-years with presidential votes and Senate returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| n_senate_states_2024 | 29 | states | count of states in the main Senate sample | states with a contested Senate race in 2024 | 2024 |   |   | none (full counts) | County election returns |   |
| n_studies | 19 | studies | count of studies with the president and House vote items | ANES presidential-election studies | 1952-2024 |   |   | none (count) | ANES Cumulative Data File |   |
| net_1972 | +20.4 | percentage points | weighted mean of the House Democratic vote minus the presidential Democratic vote, in points (the net effect of splitting on the House vote) | respondents who reported a major-party presidential vote and a major-party House vote | 1972 | 95% CI 17.7 to 23.2 | 1,293 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| net_1992 | +2.1 | percentage points | weighted mean of the House Democratic vote minus the presidential Democratic vote, in points (the net effect of splitting on the House vote) | respondents who reported a major-party presidential vote and a major-party House vote | 1992 | 95% CI −0.6 to 4.9 | 1,126 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| net_1996 | −9.1 | percentage points | weighted mean of the House Democratic vote minus the presidential Democratic vote, in points (the net effect of splitting on the House vote) | respondents who reported a major-party presidential vote and a major-party House vote | 1996 | 95% CI −12.0 to −6.1 | 926 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| net_2024 | −1.3 | percentage points | weighted mean of the House Democratic vote minus the presidential Democratic vote, in points (the net effect of splitting on the House vote) | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI −2.3 to −0.2 | 3,515 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| plateau_hi | 29.5% | percent of voters | highest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1972-1988 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| plateau_lo | 24.8% | percent of voters | lowest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1972-1988 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| pre_hi | 17.8% | percent of voters | highest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1952-1968 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| pre_lo | 12.6% | percent of voters | lowest of the yearly shares who split, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1952-1968 |   |   | none (summary of the yearly estimates) | ANES Cumulative Data File |   |
| ratio_hi | 1.3 | ratio of votes | upper bound of the totals screen: down-ballot total votes over presidential total votes | county races | 1992-2024 |   |   | none (full counts) | County election returns |   |
| ratio_lo | 0.7 | ratio of votes | lower bound of the totals screen: down-ballot total votes over presidential total votes | county races | 1992-2024 |   |   | none (full counts) | County election returns |   |
| rdh_1972 | 25.0% | percent of voters | weighted share who voted Republican for president and Democratic for the House | respondents who reported a major-party presidential vote and a major-party House vote | 1972 | 95% CI 22.6% to 27.3% | 1,293 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| rdh_1988 | 18.3% | percent of voters | weighted share who voted Republican for president and Democratic for the House | respondents who reported a major-party presidential vote and a major-party House vote | 1988 | 95% CI 15.9% to 20.6% | 1,030 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| rdh_1996 | 4.3% | percent of voters | weighted share who voted Republican for president and Democratic for the House | respondents who reported a major-party presidential vote and a major-party House vote | 1996 | 95% CI 2.8% to 5.7% | 926 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| rdh_2020 | 4.6% | percent of voters | weighted share who voted Republican for president and Democratic for the House | respondents who reported a major-party presidential vote and a major-party House vote | 2020 | 95% CI 3.8% to 5.4% | 5,167 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| rdh_2024 | 1.7% | percent of voters | weighted share who voted Republican for president and Democratic for the House | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI 1.1% to 2.3% | 3,515 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| rise_h_2012_2016 | +5.5 | percentage points | change in the weighted share who split, 2016 minus 2012 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2012 to 2016 | 95% CI 3.2 to 7.7 | 5,639 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| s_mode_diff_2012 | +1.1 | percentage points | web minus in-person difference in the weighted share who split, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2012 | 95% CI −2.2 to 4.4 | 2,814 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| s_mode_diff_2016 | +3.7 | percentage points | web minus in-person difference in the weighted share who split, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2016 | 95% CI −0.6 to 8.0 | 1,625 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| s_mode_diff_2024 | −1.7 | percentage points | web minus in-person difference in the weighted share who split, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2024 | 95% CI −5.8 to 2.5 | 1,356 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| s_web_rise_2012_2016 | +2.5 | percentage points | difference in weighted shares who split, 2016 minus 2012 (separate samples) | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2012 to 2016, web respondents, president and Senate | 95% CI −0.5 to 5.5 | 3,155 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| screen_sens_house | 0.5 | percentage points | largest yearly change in the share of divided counties if the totals screen is dropped | counties in the main House sample | 1992-2024 |   |   | none (full counts) | County election returns |   |
| screen_sens_senate | 1.3 | percentage points | largest yearly change in the share of divided counties if the totals screen is dropped | counties in the main Senate sample | 1992-2024 |   |   | none (full counts) | County election returns |   |
| senate_between_2024 | 83% | percent of the mean square | share of the vote-weighted mean square of the gap that is the state mean gap, corrected by n/(n-1) | counties in a contested Senate race, in states with at least two such counties | 2024 |   | 1,749 | none (full counts) | County election returns |   |
| senate_between_hi | 91% | percent of the mean square | highest yearly corrected share of the mean square of the gap that is the state mean gap | counties in a contested Senate race, in states with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| senate_between_lo | 64% | percent of the mean square | lowest yearly corrected share of the mean square of the gap that is the state mean gap | counties in a contested Senate race, in states with at least two such counties | 1992-2024 |   |   | none (full counts) | County election returns |   |
| senate_chg_2008_2012 | −1.8 | percentage points | change in the weighted share who split, president and Senate, 2012 minus 2008 (two separate samples) | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2008 to 2012 | 95% CI −5.2 to 1.6 | 3,600 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| senate_cov_hi | 74% | percent of presidential two-party votes | highest yearly share of the presidential two-party votes of the 48 contiguous states cast in the main Senate sample | counties in the 48 contiguous states with a contested Senate race | 1992-2024 |   |   | none (full counts) | County election returns |   |
| senate_cov_lo | 49% | percent of presidential two-party votes | lowest yearly share of the presidential two-party votes of the 48 contiguous states cast in the main Senate sample | counties in the 48 contiguous states with a contested Senate race | 1992-2024 |   |   | none (full counts) | County election returns |   |
| senate_dem_rep_1996 | 369 | counties | count of counties won by the Democrat for president and the Republican for the Senate | counties in the 48 contiguous states with a contested Senate race | 1996 |   |   | none (full counts) | County election returns |   |
| senate_dem_rep_2020 | 22 | counties | count of counties won by the Democrat for president and the Republican for the Senate | counties in the 48 contiguous states with a contested Senate race | 2020 |   |   | none (full counts) | County election returns |   |
| senate_dem_rep_2024 | 8 | counties | count of counties won by the Democrat for president and the Republican for the Senate | counties in the 48 contiguous states with a contested Senate race | 2024 |   |   | none (full counts) | County election returns |   |
| senate_div_1992 | 30.9% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 1992 |   | 1,824 | none (full counts) | County election returns |   |
| senate_div_1996 | 20.2% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 1996 |   | 2,288 | none (full counts) | County election returns |   |
| senate_div_2000 | 21.1% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2000 |   | 1,858 | none (full counts) | County election returns |   |
| senate_div_2004 | 29.6% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2004 |   | 2,006 | none (full counts) | County election returns |   |
| senate_div_2008 | 24.4% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2008 |   | 2,055 | none (full counts) | County election returns |   |
| senate_div_2012 | 18.2% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2012 |   | 1,843 | none (full counts) | County election returns |   |
| senate_div_2016 | 6.2% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2016 |   | 1,989 | none (full counts) | County election returns |   |
| senate_div_2020 | 1.9% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2020 |   | 2,212 | none (full counts) | County election returns |   |
| senate_div_2024 | 3.0% | percent of counties | share of counties whose presidential winner differs from the Senate winner | counties in the 48 contiguous states with a contested Senate race | 2024 |   | 1,749 | none (full counts) | County election returns |   |
| senate_fall_0812 | 6.2 | percentage points | 2008 share of divided counties minus 2012 share, Senate | counties in the 48 contiguous states with a contested Senate race | 2008 to 2012 |   |   | none (full counts) | County election returns |   |
| senate_fall_1216 | 11.9 | percentage points | 2012 share of divided counties minus 2016 share, Senate | counties in the 48 contiguous states with a contested Senate race | 2012 to 2016 |   |   | none (full counts) | County election returns |   |
| senate_mad_1992 | 15.9 | points of margin | vote-weighted mean absolute difference between the Senate margin and the presidential margin | counties in the 48 contiguous states with a contested Senate race | 1992 | 95% CI 12.1 to 21.1 | 1,824 | presidential two-party votes in the county | County election returns |   |
| senate_mad_2024 | 4.6 | points of margin | vote-weighted mean absolute difference between the Senate margin and the presidential margin | counties in the 48 contiguous states with a contested Senate race | 2024 | 95% CI 3.4 to 6.0 | 1,749 | presidential two-party votes in the county | County election returns |   |
| senate_r_1992 | +0.63 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the Senate margin | counties in the 48 contiguous states with a contested Senate race | 1992 | 95% CI 0.47 to 0.79 | 1,824 | presidential two-party votes in the county | County election returns |   |
| senate_r_2024 | +0.98 | correlation coefficient, from -1 to +1 | vote-weighted correlation between the county presidential margin and the Senate margin | counties in the 48 contiguous states with a contested Senate race | 2024 | 95% CI 0.97 to 0.99 | 1,749 | presidential two-party votes in the county | County election returns |   |
| senate_rep_dem_1996 | 94 | counties | count of counties won by the Republican for president and the Democrat for the Senate | counties in the 48 contiguous states with a contested Senate race | 1996 |   |   | none (full counts) | County election returns |   |
| senate_rep_dem_2020 | 21 | counties | count of counties won by the Republican for president and the Democrat for the Senate | counties in the 48 contiguous states with a contested Senate race | 2020 |   |   | none (full counts) | County election returns |   |
| senate_rep_dem_2024 | 45 | counties | count of counties won by the Republican for president and the Democrat for the Senate | counties in the 48 contiguous states with a contested Senate race | 2024 |   |   | none (full counts) | County election returns |   |
| senate_rms_2024 | 6.1 | points of margin | vote-weighted root mean square of the Senate margin minus the presidential margin | counties in a contested Senate race, in states with at least two such counties | 2024 |   | 1,749 | none (full counts) | County election returns |   |
| senate_rms_in_2024 | 2.5 | points of margin | vote-weighted root mean square of the gap after subtracting each state mean gap, corrected by n/(n-1) | counties in a contested Senate race, in states with at least two such counties | 2024 |   | 1,749 | none (full counts) | County election returns |   |
| senate_sens_max | 1.0 | percentage points | largest yearly difference in the share of divided counties between the main sample and all returns, Senate | counties with Senate returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| share_house_screen | 2.5% | percent of county-years | share removed by the totals screen | county-years with presidential votes and House returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| share_senate_screen | 2.1% | percent of county-years | share removed by the totals screen | county-years with presidential votes and Senate returns | 1992-2024 |   |   | none (full counts) | County election returns |   |
| split_h_1952 | 12.6% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1952 | 95% CI 10.5% to 14.6% | 1,009 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_1972 | 29.5% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1972 | 95% CI 27.1% to 32.0% | 1,293 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_1992 | 22.3% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 1992 | 95% CI 19.9% to 24.8% | 1,126 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2008 | 16.7% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2008 | 95% CI 14.1% to 19.3% | 1,222 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2008_ftf | 16.8% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2008, in-person respondents | 95% CI 14.2% to 19.4% | 1,222 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2012 | 9.8% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2012 | 95% CI 8.5% to 11.1% | 3,501 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2012_ftf | 11.0% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2012, in-person respondents | 95% CI 8.5% to 13.6% | 1,065 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2012_web | 9.2% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2012, web respondents | 95% CI 7.7% to 10.7% | 2,436 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2016 | 15.3% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2016 | 95% CI 13.4% to 17.1% | 2,138 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2016_ftf | 10.2% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2016, in-person respondents | 95% CI 7.2% to 13.1% | 619 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2016_web | 17.4% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2016, web respondents | 95% CI 15.1% to 19.6% | 1,519 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2020 | 11.4% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2020 | 95% CI 10.1% to 12.6% | 5,167 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2024 | 4.7% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2024 | 95% CI 3.7% to 5.7% | 3,515 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_h_2024_ftf | 5.3% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2024, in-person respondents | 95% CI 2.8% to 7.8% | 579 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_h_2024_other | 3.7% | percent of voters | weighted share whose reported votes were for different parties, president and House | 2024 panel and paper respondents with a major-party presidential and House vote | 2024 | 95% CI 2.4% to 4.9% | 1,709 | weight_postelection (VCF9999) | ANES Cumulative Data File |   |
| split_h_2024_web | 5.0% | percent of voters | weighted share whose reported votes were for different parties, president and House | respondents who reported a major-party presidential vote and a major-party House vote | 2024, web respondents | 95% CI 3.4% to 6.6% | 1,227 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| split_s_1972 | 28.5% | percent of voters | weighted share whose reported votes were for different parties, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 1972 | 95% CI 25.3% to 31.7% | 765 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_s_2008 | 12.9% | percent of voters | weighted share whose reported votes were for different parties, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2008 | 95% CI 9.9% to 15.9% | 786 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_s_2012 | 11.1% | percent of voters | weighted share whose reported votes were for different parties, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2012 | 95% CI 9.5% to 12.6% | 2,814 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_s_2020 | 7.2% | percent of voters | weighted share whose reported votes were for different parties, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2020 | 95% CI 5.9% to 8.5% | 2,879 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| split_s_2024 | 6.8% | percent of voters | weighted share whose reported votes were for different parties, president and Senate | respondents who reported a major-party presidential vote and a major-party Senate vote (states with a Senate race) | 2024 | 95% CI 5.4% to 8.3% | 2,525 | weight_postelection (VCF9999) in 1996, 2000, 2004, 2008, 2016, 2020 and 2024 and VCF0009z in the other studies including 2012; VCF0009z equals 1 for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted | ANES Cumulative Data File |   |
| web_drop_2016_2024 | 12.4 | percentage points | decrease in the weighted share who split, 2016 minus 2024 (two separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2016 to 2024, web respondents | 95% CI 9.6 to 15.2 | 2,746 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |
| web_rise_2012_2016 | +8.2 | percentage points | difference in weighted shares who split, 2016 minus 2012 (separate samples) | respondents who reported a major-party presidential vote and a major-party House vote | 2012 to 2016, web respondents, president and House | 95% CI 5.4 to 10.9 | 3,955 | weight_ftf (VCF0009x) for in-person respondents and weight_web (VCF0009y) for web respondents | ANES Cumulative Data File |   |

## Definitions

- Survey weights: Numbers that scale each respondent so the sample matches the population on known traits such as age, race, education and region. A weighted average counts a respondent with a large weight for more than one with a small weight.
- Effective sample size: The number of equally weighted respondents that would give the same precision as the weighted sample. It is smaller than the raw count when the weights vary a lot, and it sets how wide the confidence interval is.
- Percentage point: The unit for the difference between two percentages. A change from one share to another is stated in points, not in percent, so that absolute and relative change are not confused.
- Survey mode: How respondents were interviewed: in person, by phone, on paper or online. Mode can change answers, so a change in mode can look like a change in opinion.
- Correlation: A number from minus 1 to plus 1 for how closely two measures move together in a straight-line pattern. Zero means no straight-line pattern; a correlation does not say that one measure causes the other.
- County two-party margin: The Democratic vote minus the Republican vote, divided by the sum of the two, so a positive value is a Democratic lead. Votes for other candidates are left out.

## Methods

Individuals, sample. ANES Cumulative Data File respondents in the 19 presidential-election studies from 1952 to 2024 who reported a vote for the Democratic or Republican presidential candidate (VCF0704 coded 1 or 2) and for the Democratic or Republican candidate for the House (VCF0707 coded 1 or 2) and who have a weight: 29,103 respondents. The Senate series uses VCF0708 and covers 20,334 respondents in states with a Senate race. Voters for other presidential candidates, respondents who skipped a race and non-voters are left out. Votes are self-reported; the file has no validated vote.

Individuals, estimand. A respondent splits when the two reported votes are for different parties. The yearly estimate is the weighted share who split, in percent. The two directions are the weighted shares who voted Democratic for president and Republican for the House and the reverse; the net effect is the weighted mean of the House Democratic vote minus the presidential Democratic vote, in points. The president and House split is rebuilt from VCF0704 and VCF0707 in every study because VCF0709 (the combined item) is missing for 2024. In the 18 studies from 1952 to 2020 the rebuilt code equals VCF0709 for all 25,637 respondents with both, whatever their weight; 2 respondents in 1984 have VCF0709 but a missing vote item and are left out.

Weights and intervals. The vote items are post-election, so the all-interview estimates use weight_postelection (VCF9999) in the studies that have it (1996, 2000, 2004, 2008, 2016, 2020 and 2024) and VCF0009z in the others, including 2012, which has no post-election weight in the file. VCF0009z equals one for every respondent in 1952, 1956, 1964, 1968, 1972, 1980, 1984 and 1988, so those studies are unweighted. 64 respondents with both votes in 2016, 2020 and 2024 lack the post-election weight and are left out. Intervals are 95% intervals from the Kish effective sample size with a normal approximation, which treats the weighted sample as a simple random sample and ignores the strata and clusters of the sampling design. Differences between two estimates (two studies, or the two interview modes in one study) combine the two standard errors in quadrature. A yearly cell needs at least 100 respondents and an effective sample of at least 100; no cell was dropped.

Mode. The in-person and web estimates use weight_ftf and weight_web (VCF0009x and VCF0009y), the full-sample in-person and web weights, because the cumulative file has no post-election mode weights; the all-interview and mode estimates for one study therefore use different weights. The 2008 study was interviewed in person only, and its in-person estimate is used for the 2008 to 2012 comparison among in-person respondents. The 2020 study has no mode weights, so it enters only the all-interview series. The 2024 mode weights cover the newly recruited in-person and web samples; the 1,709 panel and paper respondents with both votes are in the all-interview estimate and in neither mode.

Places, sample. County presidential, House and Senate returns for the nine presidential elections from 1992 to 2024 in the 48 contiguous states (Heideman 2026, version 1.0.0; the presidential rows come from the same file). Oglala Lakota County, South Dakota, appears under two codes (46113 and 46102); the build uses 46102. Rule 1: a county needs presidential two-party votes and returns for the office, and is left out for an exact tie in either race; for Jackson County, Missouri, in 2004, 2008, 2012, 2016, 2020 and 2024, because the file's county rows leave out the part of the county in Kansas City (the file's presidential two-party votes for the county are 55% to 59% of the project's other presidential file in 2004 to 2020, and in 2024 that file reports Kansas City separately); for the Senate races in which the file codes an independent as a Democrat (Maine and Vermont 2012, Nebraska 2024), because the same candidates are coded as independents in other years (123 county-years); and for a House county flagged excludes_unopposed_seat (57 county-years). Rule 2, the totals screen: the office's total votes in the county are between 0.7 and 1.3 times its presidential total votes and the row is not flagged totals_possibly_inflated. It removes 687 of 27,567 House county-years with returns and 398 of 18,645 Senate county-years, among them Iowa 2012 House (99 counties, each vote counted twice), Georgia Senate 1992 and 2008 (158 and 157 counties; the file holds a later runoff round) and Louisiana Senate 1992 (61 counties; the October primary); of the other 588 House and 22 Senate county-years, 150 House county-years would otherwise be in the main sample. Dropping the screen changes the yearly share of divided counties by at most 0.5 points for the House and 1.3 for the Senate. Rule 3, a two-party race: the Democratic and Republican candidates together won at least 80% of the votes in the race (fails in 14 House races and 1 Senate race that have candidates of both parties). A House race is a district (a county can hold parts of several districts, and every district part has to qualify); the district has to be identified in the file and cannot have been decided in a later round. Where the file gives no district (Nevada and Washington in 2000 to 2008, parts of Iowa, Arizona, Delaware and New York), the county counts as one block that qualifies when the two parties hold at least 80% of its votes and as contested when it lists as many Democratic as Republican candidates, at least one of each. A Senate race is the state; special Senate elections are not in the file. Rule 4, a contested race (the main sample): both the Democratic and the Republican candidate received votes, in every district part for the House. Among the county-years that pass rules 1 and 2, rules 3 and 4 remove 3,097 House and 295 Senate county-years. The sensitivity sample, all returns, applies rules 1 to 3 and keeps counties in uncontested two-party races.

Places, estimands. The margin is the Democratic minus the Republican votes over their sum. A county is divided when the sign of the presidential margin differs from the sign of the down-ballot margin. The share of counties counts each county once; the share of votes weights each county by its presidential two-party votes. The correlation across counties is weighted by presidential two-party votes (the county-equal version is in the text). The gap is the down-ballot margin minus the presidential margin in points; the average absolute gap and the root mean square are vote-weighted. The shared-shift decomposition subtracts each district's (House, counties wholly inside one district) or state's (Senate) vote-weighted mean gap and compares the mean squares before and after; districts and states with one county are left out, and the part inside each unit is multiplied by n over n minus one for a unit of n counties.

Places, intervals. County returns are full counts, so shares of counties and votes carry no sampling interval. The intervals on the correlation and the average gap are percentile intervals from a bootstrap that resamples whole states (2000 replicates, seed 12345), which shows how much each statistic depends on which states are in the sample and treats states as independent.

Benchmark and region. The certified 2024 Democratic share of the two-party presidential vote is computed from the state presidential returns for all states and the District of Columbia. The South is the Census Bureau's South region among the contiguous states: AL, AR, DE, FL, GA, KY, LA, MD, MS, NC, OK, SC, TN, TX, VA and WV.

## What these data cannot show

- County returns cannot identify who splits a ticket.
- A county in which the two winners agree can contain many voters who split in opposite directions, and a divided county can arise from close races and unequal turnout with few splitters.
- Robinson [6] showed that a correlation across places can differ in size and sign from the relationship among the individuals who live in them.
- The ANES has state geography only, so it cannot say where individual splitting is highest.
- Amlani and Algara [7] study nationalization in county presidential, senatorial and gubernatorial returns from 1872 to 2020, a longer period and a different measure than the comparisons here.
- The ANES measure is self-reported.
- Respondents describe their votes after the election, and the file has no validated vote.
- The ANES voters in the 2024 sample are 55.3% (95% CI 53.0% to 57.7%) Democratic in the major-party presidential vote against 49.2% in the certified national count, so self-reported votes lean Democratic.
- A lean that differed between voters who split and voters who did not would change the rate of splitting, and the chapter cannot say whether it does.
- The samples are respondents who reported a major-party vote in both races, so voters who chose a third-party candidate, left a race blank or did not vote are out.
- The Cooperative Election Study file used in this book has no House, Senate or governor vote choice, so it gives no second individual-level source for 2006 to 2024.
- The full cumulative file has those items and would add that check, but it is not part of this build.
- The chapter describes and does not explain.
- Incumbency, candidate quality and redistricting are possible reasons for the fall in divided counties and for the shared shifts by district and state, and nothing here tests them.
- The county fall from 2008 to 2012 comes between two elections separated by the 2010 midterm and by redistricting after the 2010 census, and timing alone does not say which of these matters, if any.
- Planned, Candidate extremity and vote share (https://vishalsingh.org/politics/candidate-extremity-and-vote-share; planned), a planned chapter, asks whether more extreme House candidates lose vote share.
- The county file holds only president, House and Senate, so it says nothing about governors, state legislators or local offices, where Kuriwaki [5] finds more splitting than in Congress.
- The county comparison depends on its rules and on the file.
- The main sample leaves out uncontested races, and uncontested seats are not a random draw of places.
- The file has defects that the rules remove or work around, such as the missing Kansas City part of Jackson County, runoffs stored as general elections and an Iowa file that double counts votes, and others may remain.
- The House samples use different district maps in different decades, and the Senate samples use different states in different elections.
- Presidential margins leave out third-party votes, which were a larger share of the vote in 1992 and 1996 than in later elections.
- Alaska and Hawaii are not in the county file.
- County returns are full counts and carry no sampling interval.
- The intervals on the correlations treat states as independent, and the shared-shift decomposition describes where the gap lies without saying why it lies there.

## References

1. Kish, Leslie (1965). Survey Sampling. John Wiley and Sons.
2. Burden, Barry C.; Kimball, David C. (2002). Why Americans Split Their Tickets: Campaigns, Competition, and Divided Government. University of Michigan Press. https://doi.org/10.3998/mpub.22995
3. Jacobson, Gary C. (2015). It's Nothing Personal: The Decline of the Incumbency Advantage in US House Elections. The Journal of Politics 77(3): 861-873. https://doi.org/10.1086/681670
4. Hopkins, Daniel J. (2018). The Increasingly United States: How and Why American Political Behavior Nationalized. University of Chicago Press. https://doi.org/10.7208/chicago/9780226530406.001.0001
5. Kuriwaki, Shiro (2026). Ticket Splitting in a Nationalized Era. The Journal of Politics 88(1): 47-62. https://doi.org/10.1086/734263
6. Robinson, W. S. (1950). Ecological Correlations and the Behavior of Individuals. American Sociological Review 15(3): 351-357. https://doi.org/10.2307/2087176
7. Amlani, Sharif; Algara, Carlos (2021). Partisanship & nationalization in American elections: Evidence from presidential, senatorial, & gubernatorial elections in the U.S. counties, 1872-2020. Electoral Studies 73: 102387. https://doi.org/10.1016/j.electstud.2021.102387

## Provenance

- Pipeline version: 1.0.0
- Build script: book3/chapters/down-the-ballot/build.py (sha256 6538154e3cca6a785c4f063ccdbd25876f84879208ec8869d3738b624c373603)
- Built on: 2026-10-03
- Site commit: 16414b2c7257546a7042d0b1734657f208999f60

Inputs:

| File | Size (bytes) | SHA-256, first 1 MB | SHA-256, last 1 MB |
| --- | ---: | --- | --- |
| data/anes/anes_cdf_clean.parquet | 15,640,720 | b3f0c2d8ae5673b2c40cf6df71318ea3f712cd845c4f1aad0460f28d1b022643 | 04f06dae56b65649291caf6cf77aab9767d9c92d0c2669c6d3655d9063970583 |
| data/county/county_results_1990_2024.parquet | 6,554,860 | 2e4ea32b709fb41c3a006bf13716ffbae4fb4a80932690dacc588ad19be98b47 | 3e146fd50172039009ba8729d0e96e560fa268de208f4b780950bf45cd292b67 |
| data/county/county_results_1990_2024_long.parquet | 2,836,074 | 650f9dabffe29f9b255fb32c44b7472700a2d7e4aabc6d183cbe3ae00b455c78 | b384a8ab4071e715877cbffda146db5a57e5ec145308bb062d0a363bb146051a |
| data/county/pres_county_1868_2024.parquet | 6,295,675 | bec11c7a0cb5d4180bbd6809d048bc892dd00dfcdde527fa4da871b1dd3f835f | b2a4f000f2eea72d09af8939555289e924875cca40cd95ec8869104cd575bed7 |
| data/state/1976-2024-president.csv | 514,108 | 9936410a6dd4ecc8be7fe202c6dff5b5f8fee59d88f35ab542ed12879941dcb7 | 9936410a6dd4ecc8be7fe202c6dff5b5f8fee59d88f35ab542ed12879941dcb7 |

Outputs:

| File | SHA-256 |
| --- | --- |
| facts.json | 38bbe58284f092485c3f67187db287401e48860b36b61d9d4c60c22c09997a6c |
| figures/both_measures.json | 9892edbb61e66c7c0f44e01aeded6419a01424ab8fbfb50aade209b974e348c2 |
| figures/county_map.json | 442fcc78af818eaa31e4b6fe54a8fde62a1c0a3563041d032ef5e4488a4be1a6 |
| figures/county_winners.json | ee937b2b23cdd9c9a628626a2df0b180863899c7217e4c8c32268b8e68410ed2 |
| figures/coverage.json | b17645931a1a0714b42237bfe7b42382751241bd561faf227068d0a874a087a5 |
| figures/gap_components.json | de16ff2b733115558a93ae08feca81f35dc9988f476472565ef40fab2c43ea2d |
| figures/margin_tracking.json | 0f4736c57b5b35522f831629b696abea3ccc99891f48199d775d813865b15633 |
| figures/split_by_mode.json | d2e3d7a72917536510154b1c25e9e4b753dafbe13e50a73d30d188f548fa5ff2 |
| figures/split_by_year.json | d36e5d8fd3a1633d1d4fc44aceab2326c4bb25282d95e6dd3b8c8327903b256d |
| figures/split_direction.json | e9b666a9d01eae141cc896273f8b293057e7753b7a496d69a4892bd4dad312b1 |
| meta.json | ef058a8e743433894c233fb570b00d2b2835c2416d5d4f9729c588b29e0ee78b |
| public/data/down-the-ballot/divided_counties.json | 2122b83b544b3f463ae907f31b5a6a0f32ddb2ceab0a259b663a82d97800e19c |
| refs.json | 01365855b2f9ea94c99d3758a1e875b8890d4306c4faf60f703757e0f3b5b092 |

## Machine formats

- Report (HTML): https://vishalsingh.org/politics/down-the-ballot/report
- Report (Markdown): https://vishalsingh.org/politics/down-the-ballot/report.md
- Every estimate (JSON): https://vishalsingh.org/politics/report/down-the-ballot/facts.json
- Table 1, figure "split_by_year" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/split_by_year.json
- Table 2, figure "split_by_mode" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/split_by_mode.json
- Table 3, figure "split_direction" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/split_direction.json
- Table 4, figure "county_winners" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/county_winners.json
- Table 5, figure "county_map" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/county_map.json
- Table 6, figure "margin_tracking" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/margin_tracking.json
- Table 7, figure "gap_components" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/gap_components.json
- Table 8, figure "both_measures" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/both_measures.json
- Table 9, figure "coverage" (JSON): https://vishalsingh.org/politics/report/down-the-ballot/figures/coverage.json
- Payload of "county_map" (JSON): https://vishalsingh.org/politics/data/down-the-ballot/divided_counties.json
- Index of every report: https://vishalsingh.org/politics/llms.txt; all reports in one file: https://vishalsingh.org/politics/llms-full.txt