There are 180 state legislative seats up for election in Missouri in 2024. Across those, 55 incumbents (22 Democrats and 33 Republicans) did not file to run for re-election. That is more than the average number of retirements in Missouri from 2010 to 2022 (53.0). In 2022, 49 incumbents (6 Democrats and 43 Republicans) did not run for re-election. Two state legislative seats are vacant.

Twenty-seven incumbents out of the 123 running will face primary challengers. That is the third-most since 2010, after 2012 and 2022, which each had 35 incumbents who faced primary challengers.

There are 68 total contested primaries (with more than one candidate)—19 Democratic and 49 Republican. The average number of contested primaries from 2010 to 2022 was 69.86. The year with the fewest primaries was 2014, which had 49 (16 Democratic and 33 Republican). 2010 and 2012 each had 86 contested primaries, the highest number during that span.