Missouri took two distinct paths after the 2020 census. Congressional lines were drawn by the General Assembly. After months of debate, lawmakers approved HB 2909 on May 11, 2022. Governor Mike Parson signed it one week later, immediately putting an eight-district plan in place for the 2022 midterms. That same day, Republican candidate Paul Berry III and others sued in Berry v. Ashcroft II, alleging one-person-one-vote and racial gerrymandering violations. A three-judge federal panel denied emergency relief on May 9, 2022, and dismissed the case on July 8, 2022, leaving the map intact for 2024 while appeal deadlines passed. The General Assembly adopted a redrawn mid-decade congressional map on Sept. 12, 2025, in a special session convened on August 29.

Gov. Kehoe signed the map (HB 1) on Sept. 28, 2025. The map immediately faced both a constitutional challenge and a citizen referendum petition effort. The Missouri Supreme Court ruled(opens in new tab) unanimously on September 3, 2026, that a referendum petition filed by opponents was valid, that HB 1 had therefore never taken effect, and that the 2022 map remains in force for the November 2026 general election, with HB 1's fate to be decided by voters at the ballot box. Attorney General Catherine Hanaway announced an immediate appeal to the U.S. Supreme Court.

State legislative districts were set by citizen and judicial commissions. The House Independent Bipartisan Citizens Commission unanimously adopted a 163-seat map on January 19, 2022.  After the Senate commission deadlocked, a six-judge Judicial Redistricting Commission filed a 34-district Senate plan on March 15, 2022. Only the Senate map drew litigation: in Faatz v. Ashcroft, two voters claimed it split Buchanan County and Hazelwood in violation of the Missouri Constitution. A Cole County judge upheld the plan in September 2023, and the Missouri Supreme Court affirmed on February 14, 2024, concluding the map satisfied all constitutional criteria. With no challenges to the House map and the high court’s ruling on the Senate plan, both 2022 legislative maps remain in force for the rest of the decade.