The quick progression of domestic partnership laws in the state came soon after, with a domestic partnership law in 2007. An "everything but marriage" expansion was later upheld by voters years later.
In October, a University of Washington poll found that an increasing number of people in the state support same-sex marriage. About 43 percent of respondents said they support gay marriage, up from 30 percent in the same poll five years earlier. Another 22 percent said they support giving identical rights to gay couples, without calling the unions "marriage."
If a challenge to gay marriage law was on the ballot, 55 percent said they would vote to uphold the law. And 38 percent said they would vote to reject a gay marriage law.
Same-sex marriage also has the backing of several prominent Pacific Northwest businesses, including Microsoft, Nike and Starbucks.
In Seattle's Capitol Hill neighborhood on Wednesday, 27-year-old Nicolle Edwards said that the possibility of a referendum to the soon-to-be new law was a concern, but that she was happy her lawmakers approved gay marriage.
"Any step in the direction of equal rights is something to celebrate," said Edwards, who is gay.
The gay marriage bill is Senate Bill 6239.
Follow Rachel La Corte at http://www.twitter.com/RachelAPOly . AP writer Manuel Valdes contributed from Seattle.
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