Census data spurred GOP’s largest partisan edge in decades
Fresh off sweeping electoral victories a decade ago, Republican politicians used census data to draw voting districts that gave them a greater political advantage in more states than either party had in the past 50 years, according to a new Associated Press analysis.
That advantage, measured by a formula designed to detect potential gerrymandering, allowed Republicans to hold decade-long majorities in some congressional delegations or statehouses even as Democrats in those states won top-ofthe-ticket races for president or statewide offices. In short: Republicans won more seats than would have been expected based on the percentage of votes they received.
The GOP’s power will be put to the test starting Thursday, when the U.S. Census Bureau releases 2020 population data that will kick off the next round of the once-a-decade redistricting process. The redrawn districts will take effect in most states starting with the 2022 elections and, if the maps survive expected court challenges, remain in place through the 2030 elections.
Though redistricting can seem wonky, it has big implications for public policy. Republicans who benefited from favorable districts this past decade used their power in state capitols to cut taxes, restrict abortion and curb union bargaining rights.
In Congress, redistricting has resulted in fewer competitive seats for both Republicans and Democrats, leaving less incentive to compromise as politicians appeal further to the right and left. With Republicans needing to gain just five seats to take control of the U.S. House from Democrats, the redistricting getting underway this year ultimately could determine the fate of President
Joe Biden’s agenda to create new national voting rights and spend more on social programs.
Like 10 years ago, Republicans will have an advantage over Democrats. The GOP will control redistricting in the pivotal states of Texas, Florida and North Carolina — three of the six states gaining seats in the U.S. House. Independent commissions will draw maps in Colorado and Montana, each gaining a seat. Oregon also is adding a seat, but majority Democrats in the House have agreed to share control of the redistricting process with Republicans.
Because of recent redistricting reforms, it could be more difficult for Republicans to maintain their advantage in some states. But in an era of increased political polarization among voters, the past decade showed that it’s “really hard for one party to win when the other party has designed the maps,” said Chris Warshaw, a political scientist at George Washington University who analyzes election data.
The AP used a mathematical formula called the “efficiency gap” to calculate the size of partisan advantage in elections for U.S. House seats and in state House and Assembly contests for the 2016, 2018 and 2020 elections.
The formula identifies which parties are more effective at turning their votes into victories. It can point to partisan gerrymandering — when a party maximizes its chances of winning elections by drawing maps that spread voters for the other party among multiple districts or pack large numbers of their political opponents into a single district. The formula also can reveal natural redistricting advantages that occur when like-minded voters cram together, such as the edge that New York Republicans get when Democrats cluster tightly in New York City.