Voters in Arizona, Nebraska, Washington and Colorado head to the polls Tuesday to decide ballot measures that would determine whether biological males can compete in girls’ and women’s school sports — and, in some states, whether they can use girls’ locker rooms.
Arizona and Nebraska already have laws on the books restricting male participation in female sports. A “yes” vote in either state would expand those existing protections. Washington and Colorado have no such statewide restrictions right now. A “yes” vote in either would create one for the first time — a notable shift in two states that typically vote Democratic.
Washington: Initiative 638
A yes vote would bar students defined as biologically male from competing in girls’ K-12 interscholastic sports. Girls seeking to participate would need documentation from a healthcare professional verifying biological sex based on “reproductive anatomy, genetic makeup, or normal endogenously produced testosterone levels.”
Under current rules, Washington athletes compete based on gender identity. That policy let a boy in Camas, Washington, switch to the girls’ team mid-season earlier this year. A no vote would leave that system in place.
Opponents, including a group called No Hate in Washington State, argue the measure discriminates against transgender students and could subject girls to invasive genital examinations. Supporters call that fearmongering, pointing out that biological sex can be verified through a routine sports physical — something high school athletes already undergo — or a simple cheek swab.
Polymarket’s market-implied probability of the initiative passing stood at 64% at the time of writing.
Colorado: Proposition 134
A yes vote would establish statewide sex-based participation rules for school sports from kindergarten through college, covering public, charter and private schools as well as colleges and universities. Athletes would generally compete on teams matching their biological sex, with exceptions for coed sports and for girls joining boys’ teams when no equivalent girls’ team exists.
The measure defines females as “a person whose biological reproductive system is organized around the production of ova” and males as “a person whose biological reproductive system is organized around the production of sperm.” Unlike Washington’s initiative, it does not require a doctor’s note or medical exam — schools would set their own verification policies, and the state education commissioner could act against districts that refuse to comply.
A no vote keeps the existing patchwork system, in which schools, districts and athletic associations set their own policies under state and federal law.
Planned Parenthood and other opponents call the measure government overreach that risks “invasive gender checks for girls.” Jennifer Sey, founder of XX-XY Athletics and chair of the campaign backing Proposition 134, notes that 27 states already restrict biological males from girls’ sports and says the invasive exams opponents warn about haven’t materialized in those states.
Polymarket put the odds of passage at 55% at the time of writing.
Arizona: Proposition 318
A yes vote would expand Arizona’s existing public school sports restrictions to private schools and athletic associations, including those overseeing youth and college sports. It would also require schools and athletic associations to restrict access to restrooms, locker rooms and other private spaces based on the biological sex recorded on an original birth certificate.
The measure would let athletes sue schools and associations that knowingly violate the law, while keeping protections for coed-team competitors and not categorically barring girls from boys’ teams.
A no vote leaves Arizona’s current law in place without extending it further.
The ACLU argues the measure singles out transgender students, could subject girls to intrusive questioning about their biological sex, and exposes schools to costly lawsuits. Supporters say it closes loopholes, protects privacy and safety in locker rooms and bathrooms, and sets consistent rules for fair competition statewide.
Polymarket’s market-implied probability of passage was 82% at the time of writing — the highest of any of the four measures.
Nebraska: Constitutional Amendment
A yes vote would amend Nebraska’s Constitution to prohibit biological males from competing in girls’ and women’s school sports from K-12 through college. Schools would have to designate teams as male, female or coed, with female teams reserved for biological females. The amendment would cover public schools and colleges as well as private institutions that compete against public schools.
Nebraska already has a law doing this — Gov. Jim Pillen signed the Stand With Women Act in June 2025 — but the ballot measure would enshrine the restriction in the state constitution, making it far harder for future lawmakers to repeal.
A no vote leaves the constitution unchanged, with the existing statute remaining in effect.
Groups including OutNebraska and the Fairness for All campaign argue the amendment is unnecessary given the existing law and say transgender athletes make up a tiny share of the state’s population. Supporters, through the Fairness for Girls campaign, say enshrining the restriction protects female athletes from future legislative reversal and argue that male participation in girls’ sports creates safety risks and costs girls medals, advancement and scholarships.
No Polymarket prediction was available for the Nebraska measure at the time of writing.
