Set the winner of one or more races on the map. With the model, the other states move with them, the more so the more alike they are. With “My map”, you build the map yourself and seats are counted.
House: the 435 districts, 2026 boundaries (Census Bureau).
Nebraska, Montana, Idaho and South Dakota (Senate): the Republican faces an independent, shown in blue like the Democrats.
Chance of the Democratic or independent candidate, before and after your picks.
| Race | Forecast | With your picks | Change |
|---|
Each simulation draws one national polling error shared by every race, as in the published forecast. On top of it comes an error specific to each state, shared by the states that look alike. The likeness is Le Millénaire’s own: each state’s profile on ten criteria (white voters without a degree, graduates, Black, Hispanic and Asian residents, median age, urbanisation, religious practice, 2024 presidential vote, change from 2020 to 2024). The share of the local error that follows this link (32%) was measured on the state-by-state polling errors of the seven presidential elections from 2000 to 2024; the rest is specific to each race. Within a state, the Senate, governor and House races also share a common error: over the 2018-2024 elections, the polling errors of the Senate and governor races of the same state are correlated at 68%.
Each race keeps exactly the chance published in the forecast. The chances of a Senate and a House majority are refitted to the published figures, like the Congress scenarios on the overview page.
“My map” simulates nothing: the races you set go to the winner you chose, the others to the model’s favourite, and seats are added up. Your picks are written into the page address: copy the link to share your map.
Examples of correlation between states: Michigan and Wisconsin 0.89, Georgia and North Carolina 0.80, Nebraska and Kansas 0.97, Texas and Arizona 0.67.
Project director: William Thay
Deputy project director: Sean Scull / Pierre Clairé
Political and data analysis: Matthieu Hocque / Augustin Bataille
Data analysis, mathematics and validation: Florian Gérard-Mercier
© 2026 Le Millénaire SAS, 47 rue de Vivienne, 75002 Paris. All rights reserved. The simulators, their results, maps and texts belong to Le Millénaire. Any reproduction, even partial, is prohibited unless Le Millénaire is explicitly cited as the source: “Source: Le Millénaire, forecast.lemillenaire.org”.
The public data used remain under their own terms: U.S. Census Bureau, Association of Statisticians of American Religious Bodies (2020 Religion Census), FiveThirtyEight, MIT Election Data and Science Lab, Federal Election Commission, Clerk of the House.