The United States Supreme Court has blocked Missouri from using a newly redrawn congressional map for the November 2026 midterm elections, bringing a major legal dispute over the state’s House districts back to the Supreme Court for a third time.

The justices on Friday rejected an attempt to revive the new congressional boundaries, allowing Missouri to proceed with the districts adopted in 2022. The decision came while absentee voting was already underway, making the timing of the ruling particularly significant for election administrators and voters.

The disputed map was approved by Missouri’s Republican-led legislature in 2025 after President Donald Trump supported efforts to redraw congressional districts before the midterm elections. The new boundaries significantly changed several districts, including the Kansas City-area district represented by Democratic Representative Emanuel Cleaver.

Republican supporters of the new map argued that it should remain in place because it had already been used during Missouri’s August primary elections. They also argued that changing congressional boundaries between the primary and general elections could create problems for candidates and voters.

Opponents challenged the map through Missouri’s courts and argued that it could not legally be used without approval through a statewide referendum. The Missouri Supreme Court previously ruled that a citizen petition had created a requirement for voters to consider the issue before the new districts could take effect.

The dispute subsequently moved through the federal courts.

An appeals court had ruled in favour of using the newer congressional map, creating a conflict with the Missouri Supreme Court’s position. The case then returned to the US Supreme Court, which was asked to determine which map should govern the November election.

In its latest decision, the Supreme Court allowed the earlier Missouri Supreme Court ruling to remain in effect. The justices said that changing the congressional boundaries at such a late stage, after the election process had already begun, could cause serious disruption.

The court noted that absentee voting had already started and that election materials had been prepared using the older districts. It concluded that forcing Missouri to switch back to the 2025 map during the ongoing election could create significant administrative problems.

The ruling means Missouri voters will use the congressional districts that were in place following the 2020 census and used during the 2022 and 2024 elections, rather than the disputed 2025 map.

The case has attracted national attention because congressional redistricting has become an important political issue ahead of the November midterms. Missouri was among several Republican-led states where efforts were made to redraw House districts before the normal redistricting cycle.

The Missouri map was particularly consequential because it altered the boundaries of the Kansas City-area district held by Cleaver. Under the new boundaries, the district would have contained a substantially different electorate.

The legal dispute also illustrates the complications that can arise when election boundaries are changed close to voting day. Missouri officials had already prepared ballots and election materials under different versions of the map, while candidates had conducted campaigns under the districts used in the primary.

The Supreme Court’s decision does not settle every broader question surrounding redistricting in the United States. Instead, it determines which congressional boundaries Missouri must use for the 2026 general election while the state’s referendum process continues.

Missouri voters are expected to decide the future of the disputed map through a statewide referendum in November. Until then, the older congressional districts remain the operative boundaries for the general election.

The ruling also leaves the candidates who won their respective August primaries preparing for the general election under district boundaries that differ from those used during the primary.

For election officials, the immediate priority is implementing the Supreme Court’s decision without further disruption to the voting process. Absentee ballots have already been distributed, and voting has begun in the state.

The Missouri case has therefore become an important legal development in the 2026 US election cycle, involving questions about state election law, federal judicial authority, redistricting procedures and the practical administration of elections.