--- title: "County maps undercount Democratic early voters by about 16 points" canonical: "https://carmenaresearch.com/blog/county-maps-undercount-democratic-early-voters/" author: "Research team" publisher: "Carmena’s Overton & Electoral Research" published: "2026-10-18" topic: "Party data" license: "CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)" date_note: "Publication date is illustrative." --- # County maps undercount Democratic early voters by about 16 points Weighting each county’s early votes by its 2024 result understated the Democratic margin by 7 to 41 points in 8 states with known party. Research team · Oct 18, 2026 (date illustrative) **Key number: −16** median bias in the D−R margin, county-lean estimate vs registration (range −7 to −41) **How far the county method understated the Democratic early-vote margin** | State | Bias of county method (points) | | --- | --- | | AZ | −7.3 | | NV | −7.5 | | FL | −14.1 | | KS | −15.6 | | ME | −17.4 | | NC | −19.9 | | IA | −31 | | PA | −41 | Source: Early votes with known party in 8 states; 2024 county results. Caveat: Tested only in the 8 states where party is known from records. Data (CSV, CC BY 4.0): https://carmenaresearch.com/data/public/chart-county-bias.csv A quick way to guess the party of early voters in a state without party data is to weight each county’s early votes by how that county voted in 2024. We tested it in 8 states where the party of early voters is known. As of Oct 22, 2026, the county method understated the Democratic margin in every one of them, by 7 to 41 points, with a median of about 16. By state, the understatement in the D−R margin was: Arizona −7.3, Nevada −7.5, Florida −14.1, Kansas −15.6, Maine −17.4, North Carolina −19.9, Iowa −31.0 and Pennsylvania −41.0. ## What it means Geography misses most of what makes early voters different. Most of the Democratic tilt among early voters happens within counties: in a given county, the people who vote early are more Democratic than the county as a whole. A county average cannot see that, because it treats every early voter in a county as if they voted like the county overall. Measured another way, geography explains only a small part of the gap. Taking each state’s 2024 result as the baseline, the county method captures roughly 0 to 40% of the Democratic tilt that registration shows among early voters, and in most states well under a fifth. The rest of the tilt happens inside counties. The bias is smallest where early voting is old and universal. In Arizona and Nevada, where most voters vote early, the county method was off by about 7 points. It was largest where the early electorate is mail-heavy and skewed toward Democrats, as in Pennsylvania and Iowa. For the Senate races without party data, this sets a floor. In Michigan, Minnesota and South Carolina, a county estimate is a lower bound on how Democratic the early vote is, not an estimate of it. ## What it doesn’t mean The registration benchmark is not the truth about votes. Registration is not vote choice, and in states with many long-registered Democrats who vote Republican, registration overstates the Democratic margin. Pennsylvania’s −41 is partly that: its early voters are 67% registered Democrats. The two measures answer different questions. The county method estimates vote preference and is almost two-party, with about 1 to 2% Other. Registration splits voters into Democrats, Republicans and unaffiliated, and unaffiliated voters were 9% to 34% of early voters in these states. That is why we compare margins and two-party shares, not raw Democratic percentages. On a two-party basis the bias is −4 to −23 points, median about −11. It does not mean county maps are useless. They show where the early vote is coming from. They cannot show who within each county is voting. ## How we checked For each county (each town in Maine), we took accepted 2026 early ballots, by mail and in person, and multiplied them by that area’s 2024 presidential shares. Summing across a state gives the county-method estimate. Areas with no 2024 match took the statewide shares. Early-vote counts come from state files: the North Carolina State Board of Elections file, Maine’s absentee voter file of Oct 20, the Iowa Secretary of State’s daily statistics, and the UF Election Lab county files, which we checked against official sources where we could. 2024 results are county presidential returns; Maine uses town-level results from the state tabulation. We compared each estimate with the registered party of the same early voters, as recorded by the state, and report the difference in the D−R margin. ## Caveat Registration is not vote choice either, so the benchmark has its own bias in states with old Democratic registration, such as Pennsylvania. ## Sources 2026 early votes by county from state files via the UF Election Lab mirror; party registration of early voters in 8 states; 2024 county presidential results. - [UF Election Lab, 2026 early-vote county files](https://election.lab.ufl.edu/data-downloads/earlyvote/2026/) - [North Carolina State Board of Elections, 2026 absentee and early-vote file](https://s3.amazonaws.com/dl.ncsbe.gov/ENRS/2026_11_03/absentee_20261103.zip) - [Maine Secretary of State, voter data](https://www.maine.gov/sos/elections-voting/voter-data) - [Iowa Secretary of State, absentee statistics (congressional district)](https://sos.iowa.gov/elections/pdf/2026/general/AbsenteeCongressional2026.pdf) ## Cite this Research team. “County maps undercount Democratic early voters by about 16 points.” Carmena’s Overton & Electoral Research, Oct 18, 2026. https://carmenaresearch.com/blog/county-maps-undercount-democratic-early-voters/ Free to use with credit under CC BY 4.0. HTML version: https://carmenaresearch.com/blog/county-maps-undercount-democratic-early-voters/