2020 was the safest year for state legislative incumbents in a decade, a study finds.

Fewer 2020 incumbents lost general elections for state legislative seats than in any year in the last decade, according to a new analysis from the political website Ballotpedia.

Yet while incumbents were becoming safer in general elections, they were more vulnerable in primaries than in any year since 2012 — the last time redistricting forced many elected officials into districts with fellow incumbents — a sign of the increasing polarization of American politics, particularly in the Republican Party.

Nearly twice as many Republican state legislators lost primary contests (94) as general elections (52) last year, and nearly three times as many Democrats were ousted in November (165) as in party primaries (60).

Overall, just 227 of 4,823 incumbents who appeared on general election ballots this year lost — the smallest numbers since Ballotpedia began tracking data in 2010. Fewer state legislative incumbents typically lose in presidential election years, an indication that voters who choose one party for president stick with the same party for other offices on the ballot.

Last year’s elections also marked the first time since 1944 that only two statehouse chambers — the New Hampshire House and Senate, which both flipped from Democratic to Republican majorities — changed partisan control.

“You’d call this election a draw,” said Doug Kronaizl, who conducted the Ballotpedia study of state legislative results. “You didn’t see a bunch of flips. It was just a struggle in the trenches as far as partisan control.”

With redistricting battles looming when the Census Bureau delivers its 2020 data to states later this year, control of redistricting changed in only three states last year: New Hampshire; Vermont, where Democrats lost a veto-proof majority in the state legislature; and Virginia, where voters approved a nonpartisan redistricting commission.