In most states, redistricting is handled through the regular legislative process, with legislatures working to draw maps that are signed into law by governors. In these states, whoever controls the state government controls the redistricting process. Partisan lawmakers often draw districts in a way to disadvantage the opposing party, a process known as gerrymandering.
According to state election results compiled by Ballotpedia and Daily Kos’s Stephen Wolf and analyzed by The Washington Post, if redistricting were to occur tomorrow, Republicans would have unified control over the boundaries of 179 House districts, down from 204 before the election. That decrease is due in large part to the loss of governor’s mansions in Wisconsin and Michigan.
For simplicity’s sake, this analysis assumes that Republican Brian Kemp is declared the winner of the Georgia governor’s race, keeping that state under unified Republican control. It also assumes the passage of a ballot measure to create an independent redistricting commission in Utah, which is leading by a narrow margin.
Democrats, meanwhile, now have complete control over the boundaries of 76 seats, up threefold from just 24 before the election. The lion’s share of that shift is due to New York state, where Democrats took control of the state Senate for the first time since 2010, putting themselves in control of the state’s 27 seats in Congress. Democrats also won unitary control of state governments in Nevada and New Mexico.
Those partisan shifts mean that the number of seats under split control, where both parties have a say in the redistricting process, dropped sharply to 60 following the election.
The other significant shift was an increase in seats that will be drawn by independent commissions. Voters in Michigan and Colorado approved ballot measures creating such commissions. Voters in Utah appear to be poised to do the same, although the count remains close and the final result has not yet been called.
Former U.S. attorney general Eric H. Holder Jr., who leads the National Democratic Redistricting Committee, said on Twitter that he was “proud of our work that resulted in reform candidate victories, creation of independent commissions and making state legislatures more responsive to the people.” The NDRC had targeted elections in a number of states with an eye toward reducing Republican majorities in state legislatures.
The 2020 election will be voters' last chance to alter the compositions of their state governments before the redistricting that will happen in 2021.