A measure allowing civil unions for gay couples has cleared the Colorado Legislature and is headed to the governor’s desk, where it’s expected to be signed.

The bill won final passage Tuesday on a 39-26 House vote, with two Republicans joining all Democrats to approve it.

Once the measure is signed, Colorado will join eight states that have civil unions or similar laws. Nine states and the District of Columbia allow gay marriage.

The bill’s approval marks a significant political shift in a western state that traditionally has had deep conservative roots but has become more moderate over the past decade.

Colorado voters banned gay marriage seven years ago. That means civil unions are the only option for gay couples in the state, but a U.S. Supreme ruling on gay marriage laws could change that.