New York has become the latest and largest US state to legalise same-sex marriage in a move which gay rights campaigners hope will be a turning point for recognition of such unions across the country.
The state senate's backing of the marriage equality bill means New York, the third most populous US state, joins Connecticut, Iowa, Massachusetts, New Hampshire, Vermont and the Washington capital district in allowing gay couples to wed.
Gay weddings are expected to commence within 30 days after governor Andrew Cuomo signed the bill into law on Friday night. The Republican-controlled state senate voted 33-29 for the bill which had earlier been approved by the lower house, which has a Democratic majority.
Gay rights activists believe the vote will strengthen the campaign for marriage equality across the country, as the impact of the legislation will be felt well beyond New York.
Unlike in Massachusetts, the first state to allow gay marriage in 2004, people do not need to be residents of New York to obtain a marriage licence, so the state could attract couples from across the country.
Activists believe the state's size and New York City's international stature add to the significance of the vote.
Ross Levi, executive director of the Empire State Pride Agenda, said the law would have "a ripple effect across the nation".
"It's truly a historic night for love, our families, and democracy won," he added.
The vote was particularly emotional for many in the gay community as the gay rights movement is considered to have started in New York City with the Stonewall riots in Greenwich Village in 1969.
There was a huge street party at the Stonewall Inn overnight. Alex Kelston, 26, who works in finance in Manhattan, said: "This is the place where the movement started, and it's a way to close the loop and celebrate the full equality of gay people in New York."
Scott Redstone popped the question to his partner of 29 years, Steven Knittweis: "I said, 'Will you marry me?' And he said, 'Of course!'"
Revellers posted photos of the celebrations on Twitter, which included waving rainbow flags and dancing. The vote is likely to be celebrated at annual gay pride events this weekend, culminating with parades in New York City, San Francisco and other cities on Sunday.
Sarah Ellis, who has been in a six-year relationship with her partner, Kristen Henderson, said the new law would enable the couple, who have twin toddlers, to get married in the autumn.
"We've been waiting. We considered it for a long time, crossing the borders and going to other states," said Ellis, 39, from Long Island. "But until the state that we live in, that we pay taxes in, and we're part of that community, has equal rights and marriage equality, we were not going to do it."
In the week leading up to the vote in New York, some Republicans who opposed a similar bill in 2009 announced they were supporting it for reasons of conscience and a duty to ensure civil rights.
Pressure to back the legisation came from celebrities, athletes and New York City mayor Michael Bloomberg, who has long used his own fortune to help bankroll Republican campaigns and personally lobbied some undecided representatives.
Senator Stephen Saland, voted against the 2009 bill, said before last night's vote. "I am doing the right thing in voting to support marriage equality."
Singer Lady Gaga has been urging her 11 million Twitter followers to call New York senators in support of the bill. Following the vote, she tweeted: "I can't stop crying. We did it kids. The revolution is ours to fight for love, justice+equality. Rejoice NY, and propose. We did it!!!"
Pink tweeted: "Congratulations!!!!!!!!! About time!"
The legislation does include Republican demands for legal protections for religious groups that fear they will be hit with discrimination lawsuits if they refuse to allow their facilities to be used for gay weddings.
