As the anniversary nears Tuesday, the law's effects are noticeable if hard to measure.
Thousands of same-sex couples have wed across New York, but it's unclear just how many, partly because marriage applicants aren't required to identify themselves by gender. The wedding business is up, but some planners in New York City say it's not booming.
And while President Barack Obama announced support this year for gay marriage, no state has enacted a law allowing it since New York. And opponents note that North Carolina voters banned it.
One thing is clear: legalizing gay marriage in the cultural, media and business hub of New York City amped up the national spotlight on the issue.
"Do you know I still have people come up to me and congratulate me on my wedding?" said Carol Anastasio, who was among the first bouquet-waving, teary-eyed newlyweds when New York legalized gay marriage July 24, 2011. News crews swarmed Anastasio and Mimi Brown outside the city clerk's office in Manhattan.
"I work in a public park so I'm outdoors a lot and people will be walking a dog: 'I thought that was you! I saw you in the paper! That's great!'" said Anastasio, a city parks manager. "It's really amazing how it just continues."
New York inked its gay marriage law with a nail-biting state Senate vote on the night of June 24, 2011, after weeks of intensive lobbying by Democratic Gov. Andrew Cuomo. Exactly one month later, New York became the sixth and largest state to allow gay weddings - more than doubling the number of same-sex couples eligible to wed.
The new law was ushered in with a whirlwind of weddings that started in the minutes after midnight from Niagara Falls to New York City.
"When it became a reality in New York, that's when I think most Americans started to realize that this is something we'll all be dealing with and started thinking about it seriously," said Marty Rouse, national field director for the Human Rights Campaign. "The momentum from New York can't be underestimated. After Massachusetts becoming the first state, nothing has had that influence."
Rouse said that because of New York's size and influence, people around the country had to think seriously about what legalization meant for them and their families.
Even as Obama announced his support in May, North Carolina voters that week approved a constitutional amendment defining marriage solely as a union between a man and a woman. State lawmakers in Maryland and Washington passed same-sex marriage laws, but voters will have a final say in November over whether the measures will take effect. The issue is also on the ballot this fall in Maine and Minnesota, where opponents are ready to spend up to $20 million to keep the definition of marriage as between a man and a woman.
Opponents note that despite legislative victories in states like New York, voters have rejected gay marriage in all 32 states where it has been on the ballot.
"As it passes, people begin to realize that it's more than two people standing at the altar, it literally alters all of society," said Tony Perkins, the president of the Family Research Council.
Ahead of its passage, an analysis by the New York Senate's independent Democratic conference predicted there would be up to 66,500 same-sex weddings in the first three years that would generate $311 million in increased revenue and economic activity.
A year out, the exact number of gay couples wed statewide is unknown. New York City, where most gay people are wed in the state, did not immediately have any numbers. At least 3,424 same-sex marriages occurred outside of the city by mid-July, according to state Department of Health figures.
People involved in New York City's wedding industry report only a mild surge in business. The prevailing view among vendors is that many gay couples already had celebrated their unions before the legislation was passed. Now all they really want is the legal paperwork, not a four-tier cake.
"The kind of people who were throwing lavish parties or celebrations were celebrating with or without the piece of paper," said Sarah Cohen, owner of Blossom and Branch, a Brooklyn-based boutique floral design studio. She guessed the law's passage translated to two or three more weddings this year than she would typically handle.
The Rev. Will Mercer, a New York City-based Christian minister, said gay weddings now comprise a third of his total business - generally about 150 ceremonies a year. But at least half of them choose quiet ceremonies with only about a dozen close family members or friends.
"The wedding is part of their whole experience during their visit to the city," Mercer said.
The change was more noticeable in the "honeymoon capital" of Niagara Falls where the city clerk issued 459 marriage licenses in the year after passage, compared with 382 the previous year.
"That's business we wouldn't have had otherwise," said Sally Fedell, whose Falls Wedding Chapel is one of several in town.
But proponents say the true impact goes beyond numbers. New York City Council Speaker Christine Quinn, who married her longtime partner Kim Catullo in May, said she's been struck by the goodwill same-sex marriage has generated around the city, and not just among supporters.
"I go to places where you think based on the sign over the door: This place is conservative, they're not going to want to see the ring, ask how it was, congratulate me," she said. "Couldn't be more wrong."
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