Forty Congressional incumbents—four in the Senate and 36 in the House—did not run for re-election in 2020. Of these 40 open seats, four (10 percent) changed party hands as a result of the 2020 elections, and an additional three races were still too close to call as of Nov. 18. All four changes occurred in the House, where Democrats picked up three seats held by Republicans and Republicans picked up one seat held by a Libertarian.
The group of 40 incumbents who did not run for re-election included 10 Democrats, 29 Republicans, and one Libertarian. They represented 8.5 percent of all 470 Congressional offices up for election.
Across all 2020 Congressional elections, 16 seats changed hands. Democrats picked up two seats in the Senate while Republicans picked up one. In the House, Democrats picked up three seats while Republicans picked up 10 seats.