Leader maps colour each county by the candidate (or, for the House, the party) ahead there, shaded by their lead over second place. Shift maps show the change in the two-party margin, Democrat minus Republican, in percentage points.
In Senate and Governor races where no Democrat finished in the top two, the leading non-Republican (for example Dan Osborn in Nebraska) is counted on the Democratic side of shift calculations. Counties where either election had a House district without both a Democratic and a Republican candidate are left grey in shift maps and dropped from scatterplots.
House results are every district's vote summed by party within each county. District lines changed in several states between 2024 and 2026, so House shifts mix real movement with new matchups. Chicago is combined with suburban Cook County.
Historical results cover the 48 contiguous states, so Alaska and Hawaii are grey before 2026. Connecticut is mapped by its eight historical counties. The ACS now reports Connecticut by planning region, so its county demographics are built by adding up town estimates, with median income and age interpolated from income and age brackets. Alaska's Chugach and Copper River areas are shown together as Valdez-Cordova.
Sources: 2026 results,
civicAPI, unofficial until states certify. 2000–2024 results, Heideman (2026),
U.S. county-level election results, 1990–2024, CC BY 4.0. Demographics, US Census Bureau American Community Survey 2020–2024 5-year estimates and 2024 Gazetteer. Boundaries, US Census Bureau via us-atlas.