The Missouri Congressional Map Referendum, a veto referendum on the 2025 Republican-drawn congressional plan (HB 1), appears on the November 3, 2026 ballot as Proposition A following a unanimous Missouri Supreme Court ruling on September 3 that certified sufficient signatures and suspended the map until voter approval. The measure asks voters to uphold or repeal the mid-decade redistricting that alters districts including the Kansas City area. Conflicting federal district court orders and pending U.S. Supreme Court applications have created procedural uncertainty over map use in the general election, but the referendum itself proceeds. With the outcome closely divided, traders assign a slight edge to rejection, reflecting the competitive dynamics of voter sentiment on the legislature's redistricting changes and unresolved legal challenges that could still influence turnout or messaging in the final weeks.