With the conclusion of this year’s primary election cycle, 216 state legislative incumbents—63 Democrats and 153 Republicans—lost to primary challengers, representing 4.5% of incumbents running for re-election.

These totals include data from the final three state legislative primaries held on Sept. 13 in Delaware, New Hampshire, and Rhode Island:

• Delaware: one Republican incumbent lost;
• New Hampshire: seven incumbents lost: two Democrats and five Republicans; and,
• Rhode Island: two Democratic incumbents lost.

These numbers will likely change. There are 12 Democratic and 24 Republican primaries featuring incumbents across these three states that remain uncalled in addition to three uncalled Democratic primaries featuring incumbents in states that held elections earlier this year.

This year, Republican incumbents lost at a higher rate than Democrats. Of the 2,568 Republican incumbents who filed for re-election, 153 (6.0%) lost to primary challengers. For Democrats, 63 of the 2,273 who filed for re-election (2.8%) lost.

Forty-seven of these 216 incumbent defeats (22%) were guaranteed due to redistricting. When states redraw legislative lines, incumbents can oftentimes end up in a new district with other incumbents leading to incumbent v. incumbent primaries or general elections. Since, in these races, there are more incumbents running than nominations or seats available, at least one incumbent must lose.

You can view more information about state-specific and historic information regarding incumbent defeats by clicking “Learn More” below.