Arizona voters will decide Proposition 318 on November 3, 2026, a legislatively referred measure that expands existing state law by requiring all schools and athletic associations to designate teams and private athletic spaces such as restrooms, locker rooms, and showers according to biological sex recorded at birth on original birth certificates. The Arizona Legislature advanced the proposal earlier in 2026 along party lines, with Republican majorities supporting and Democratic members opposing. A June 2026 U.S. Supreme Court ruling upholding similar state restrictions on transgender participation in girls’ and women’s sports cleared enforcement pathways for Arizona’s prior statute and bolstered the measure’s legal footing. With limited organized opposition and the state’s partisan balance, trader pricing at 73% for passage reflects these institutional and judicial developments.