Following the Nov. 3, 2020, elections, there were 19 states where either Democrats, Republicans, or both had a net gain of seats in both the state House and Senate.
Democrats had a net gain in both chambers of six states, seeing their largest net gains in Connecticut, where Democrats picked up a net of six seats in the state House and two in the state Senate. The smallest net gains for Democrats were in Massachusetts and Missouri, with a net gain of three seats across both chambers in each state.
Republicans had a net gain in both chambers of 15 states with their largest in New Hampshire where they gained a net 57 seats in the state House and four in the Senate. Aside from Alaska, where control of the state House had yet to be determined as of Jan. 26, New Hampshire was the only state where control of a legislative chamber changed in the 2020 elections. Both the House and Senate flipped from Democratic to Republican control. The smallest net gains for Republicans were in Missouri and Oregon, with a net gain of one seat in both the House and Senate of each state.
Both Democrats and Republicans had net gains in Missouri and Vermont due to flipping seats that were either previously held by third party legislators or winning seats that were vacant at the time of the election.
The map below shows those states where one party had net gains in both state legislative chambers shaded red, blue, or purple to indicate party gains.
The table below lists these states and the net gains made by each party in both state legislative chambers. Democratic gains are shown on the left. Republican gains are shown on the right.
Across all chambers that held regular state legislative elections in 2020, Democrats had a net loss of 114 seats, Republicans had a net gain of 175, and third parties had a net loss of 14.
To learn more about these chambers and the number of legislators by party following the 2020 election, click here.