How to read it
Each triangle is a county. It leans left and turns blue where the Democratic margin grew, and leans right and turns red where the Republican margin grew. Length shows the size of the shift; the base shows how many votes were cast. Hover or tap a county for its numbers.
Data: 2000–2016 county returns from the
MIT Election Data + Science Lab; 2020 and 2024 from Tony McGovern's compilation of Fox News, Politico, Guardian and New York Times results (
github.com/tonmcg). Map:
us-atlas (Census cartographic boundaries). Margin = (Dem − Rep) ÷ total votes; shift = later margin − earlier margin, in percentage points.
Quirks: Alaska reports by state house district, so it is shown as one statewide triangle. Connecticut reported by new planning regions in 2024, so any comparison with 2024 shows Connecticut as one statewide triangle. DC wards are combined, and Kansas City and the former Bedford city, VA are folded into their counties.
2026: U.S. House results by county from the New York Times results pages (Associated Press data), downloaded 6 November 2026 while counting was still under way; the “% counted” shading shows how much of the expected vote was in. House districts are added up within each county. Races where the top two finishers weren't a Democrat and a Republican (uncontested seats, California's same-party runoffs, Alaska's race against an independent) are left out. Where a county is only partly covered by such a race, the 2024→2026 shift compares the contested part with the 2024 presidential margin in that same part, and the county is left out of other comparisons with 2026. A midterm House vote and a presidential vote are different contests, so read the 2026 shifts as a change in party strength, not a like-for-like swing.