Washington state voters have approved the state's new "everything but marriage" law, marking a significant expansion of rights for gay couples who are registered as domestic partners.
National gay-rights groups say the passage of Referendum 71 marks the first time a state's voters have approved a gay equality measure at the ballot box.
With about 69 percent of the expected vote counted Thursday in unofficial returns, R-71 was leading 52 percent to 48 percent.
The measure asked voters to approve or reject the latest expansion of the state's domestic partnership law, granting registered domestic partners additional state rights previously given only to married couples.
Full-fledged gay marriage is still not allowed under Washington law.
Results weren't known until Thursday because almost all voters in Washington cast their ballots by mail, and even those ballots postmarked on Election Day are valid. That means close elections often drag on for a few days or longer.