SEATTLE — Hundreds of same-sex couples across Washington state started picking up marriage licenses Thursday as a voter-approved law legalizing gay marriage took effect.

King County, the state’s largest, opened the doors to its auditor’s office in Seattle just after midnight to start distributing licenses. But hundreds of people had lined up hours earlier, snaking around the building on a chilly night. By Thursday afternoon, more than 450 licenses had been issued in Seattle, where the mood was festive overnight.

“We waited a long time. We’ve been together 35 years, never thinking we’d get a legal marriage. Now I feel so joyous I can’t hardly stand it,” said 85-year-old Pete-e Petersen, who with her partner, 77-year-old Jane Abbott Lighty, were the first to get a license.

After meeting 35 years ago on a blind date in Sacramento, Lighty and Petersen plan to get married Sunday.

Washington state now joins several other states that allow gay and lesbian couples to wed. Gov. Chris Gregoire and Secretary of State Sam Reed certified the election results of Referendum 74 on Wednesday, and the law took effect at 12:01 a.m. Thursday.

R-74 had asked voters to either approve or reject the state law legalizing same-sex marriage that legislators passed earlier this year. That law was signed by Gregoire in February but was put on hold pending the outcome of the election. Nearly 54 percent of voters approved the measure.

The law doesn’t require religious organizations or churches to marry gay or lesbian couples.

Because the state has a three-day waiting period, the earliest that weddings can take place is Sunday. Same-sex couples who previously were married in another state that allows gay marriage, like Massachusetts, will not have to get remarried in Washington state. Their marriages became valid here Thursday, when the law took effect.

Vicky Dalton, the Spokane County auditor, said that as of 4 p.m. Thursday, more than 760 marriage licenses had been issued statewide to same-sex couples, with more than half of them being issued in King County.