Did the Redistricting Wars Backfire on Republicans? In a Word, No.

Methodology

We calculated the number of seats gained from mid-cycle redistricting by taking the number of seats each party has won in the 2026 midterm elections, according to results from The New York Times, minus the number each party would have won with the same votes cast under the 2024 district lines, or under computer-simulated maps. The simulated maps were taken from Harvard’s ALARM Project or generated with ALARM’s redistricting algorithms. We removed race-based redistricting constraints to reflect the Supreme Court’s decision in Louisiana v. Callais.

For races that have not been called as of publication time, we show a range of likely outcomes, based on how much of the vote is still outstanding. In Louisiana, where December runoffs will decide the Fifth and Sixth Districts, we added up the votes for all Democratic candidates and all Republican candidates to project which party will win each seat.

To estimate results under 2024 district lines, or under computer-simulated maps, we take 2026 House votes for each county and district (or precinct where available). Where another map’s lines split a county, we divide its votes according to where each party’s voters were in 2024, then add them up within each 2024 or simulated district. Where a race had no Democratic or Republican candidate, we used the statewide change in vote since 2024 instead.

Across all the maps, we count a district as won by a party if that party received more than 50 percent of the two-party vote. This measure is sensitive in close races: A district decided by a fraction of a point counts as a full seat for the winner. For the simulated maps, we averaged the seats across 5,000 different plans, creating fractional seats.