Washington Governor Chris Gregoire on Wednesday will certify the state's gay marriage law.

Gregoire will be joined in Olympia by Secretary of State Sam Reed in certifying the election results.

On November 6, 54 percent of voters approved Referendum 74, which upheld a marriage equality bill approved by lawmakers and signed into law by Gregoire.

The new law will take effect on Thursday. However, Washington's three-day waiting period means the state's first weddings won't happen until Sunday.

King County Executive Dow Constantine earlier announced that the King County Recorder's Office in Seattle will open just after midnight on Thursday to begin issuing licenses to gay couples. Constantine told the AP that he'll be in the office to sign the first marriage license. Thurston County will also open at 12:01 AM Thursday.

Seattle City Hall will open for 5 hours on Sunday to begin celebrating what are expected to be the state's first gay weddings.

With nearly 2 million residents, King County is the state's most populous county, and the 14th most populous in the United States.

Voters in Maine and Maryland also approved initiatives legalizing such unions. But Maryland's law won't take effect until January 1, while Maine's law is expected to come online on Saturday, December 29.