The election saw an equal number of measures approved and rejected: seven each, plus one regional ballot issue, Ballot Measure 7A, which passed to fund a passenger rail line along the Front Range.
Amendment 87, a progressive-backed measure, passed with about 52% support, re-establishing a progressive income tax system in Colorado for the first time since 1986 by removing a constitutional provision requiring a flat tax rate. It creates six new income tax brackets, raising taxes on households and businesses earning above about $500,000 while cutting taxes on the first $100,000 of annual income.
Proposition NN passed with roughly 57% approval and is expected to generate about $330 million in its first year to boost teacher salaries, reduce class sizes, and invest in early childhood programs. The measure raises the state spending cap by $4.6 billion, effectively eliminating taxpayer refunds due under the Taxpayer Bill of Rights (TABOR) indefinitely.
Proposition 132, which passed with about 53% support, reclassifies manufacturing, distributing, or selling a list of synthetic opioids including fentanyl as a level 1 drug felony punishable by 8 to 32 years in prison, taking effect in 2027. Proposition 133 passed with roughly 62% approval, imposing mandatory life without parole for anyone convicted of child sex trafficking, effective January 1, and expanding the definition to include exchanging anything of monetary value for buying or selling sexual activity with a minor.
Proposition 134 passed with about 52% support, banning transgender athletes from competing in gender-specific sports from kindergarten through college in any school or sports association receiving state funds. Proposition 135 passed with 52% approval, prohibiting certain gender-related surgeries for minors, though no Colorado hospital says it currently performs such surgeries on anyone under 18.
Proposition 137 passed with about 52% support, initially redirecting an estimated $175–$180 million annually from existing sales taxes on sporting goods to fund environmental conservation, wildfire mitigation, and rehabilitation work, as well as outdoor recreation access grants.
Ballot Measure 7A passed with roughly 57% support in the Front Range region, approving a 0.333% sales tax increase to fund a passenger rail line connecting Fort Collins to Pueblo, projected to raise about $295 million annually and authorizing $580 million in bonds.
Among rejected measures, Amendment 81 would have required police and prosecutors to notify federal immigration authorities under certain circumstances; it failed with 55% opposed. Amendment 82, which would have prevented state and local governments from prohibiting or limiting the sale and use of natural gas, failed with 54% opposed. Amendment 83, creating a constitutional right to hunt and fish, failed with 55% opposed. Amendment 84, which would have required voters to include part of their Social Security or driver's license number on the outside of mail-ballot return envelopes, failed with 63% opposed. Amendment 85, requiring ballot questions to be written at an eighth-grade reading level, failed with 51% in favor but needing 55% to pass. Amendment 86, making it harder to change congressional district boundaries, failed with 53% opposed. Proposition 136, a conservative measure to cap the state income tax rate at 4.4%, failed with 53% opposed.
Governor-elect Phil Weiser and prominent Democratic legislators are already considering how to modify four conservative-backed measures that passed: Propositions 132, 133, 134, and 135. The Legislature could modify or even eliminate Proposition 134, which changes state law rather than the state constitution.