This year’s filing deadline for candidates running for the U.S. House of Representatives in Massachusetts’ was June 2, 2026.

This year ties with 2018 for the highest number of incumbents running in contested primaries since 2014. Five incumbents — all Democrats — are running in contested primaries. There were no incumbents in contested primaries in 2024, none in 2022, three in 2020, five in 2018, none in 2016, and two in 2014.

In total, six primaries — all Democratic — are contested this year. In total, there was one contested primary in 2024, two in 2022, five in 2020, eight in 2018, one in 2016, and three in 2014.

Not among the incumbents running for re-election is Rep. Seth Moulton (D), who is running for the U.S. Senate in Massachusetts rather than for re-election. As a result, the 6th Congressional District is open this year. Since 2014, there have been two other years in which districts were open. One district was open in 2018 and 2020, respectively.

The 6th Congressional District has attracted the most candidates. Seven candidates — six Democrats and one Republican — are running for the district.

Twenty-five candidates — 20 Democrats and five Republicans — are running for Massachusetts’ nine congressional districts. That’s 2.8 candidates per district. There were 1.4 candidates per district in 2024, 2.1 in 2022, three in 2020, 3.4 in 2018, 1.6 in 2016, and 2.2 in 2014.

The 1st, 2nd, 5th, and 7th congressional districts are guaranteed to Democrats because no Republicans will appear on the ballot. Democrats filed to run in all nine districts, meaning none are guaranteed to Republicans.

Massachusetts is holding U.S. House primaries on Sept. 1, 2026.

In Massachusetts, the winner of a primary election is the candidate who receives the greatest number of votes, even if the candidate does not receive an outright majority of votes cast.