OLYMPIA, Wash. (AP) — Washington state has approved gay marriage, joining Maine and Maryland as the first states to pass same-sex marriage by popular vote.

Voter returns released since election night show Referendum 74 has maintained its lead of 52 percent. Opponents conceded the race Thursday, while supporters declared victory a day earlier.

Gov. Chris Gregoire calls the vote "a turning point for equality."

Preserve Marriage Washington says its members were disappointed and says it will "continue to educate citizens and policymakers" that marriage is between one man and one woman.

The measure was losing in 31 of the state's 39 counties. But it had its strongest lead — 66 percent of the vote — in King County, which holds about a third of the state's voters and is home to Seattle.