NEW YORK – Hundreds of gay couples dressed in formal suits and striped trousers, gowns and T-shirts recited vows in emotion-choked voices and triumphantly hoisted their long-awaited marriage certificates on Sunday as New York became the sixth and largest state to recognize same-sex weddings.

Couples began saying “I do” at midnight from Niagara Falls to Long Island, though New York City became the sometimes raucous center of action by daybreak Sunday as couples waited on a sweltering day for the chance to exchange vows at the city clerk’s office.

Thousands of protesters rallied in several cities around the state, a signal that the long fight for recognition may not be over just yet.

But a party atmosphere reigned in the lobby of the Manhattan clerk’s office, with cheers and applause breaking out whenever a couple was handed their white-and-blue wedding certificate. Balloons floated overhead. One couple wore matching kilts; another wore sparkly crowns. Children scurried up and down the lobby; workers with bullhorns called out the numbers of each couple.

Poignant signs of pent-up emotion were common from couples who had in some cases waited for years to wed. Couples cried and voices quavered. Newlywed Douglas Robinson exclaimed, “You bet your life I do!” when asked if he would take Michael Elsasser as his spouse.

The first couple to marry in Manhattan were Phyllis Siegel, 77, and Connie Kopelov, 85, who have been together for 23 years. Kopelov arrived in a wheelchair and stood with the assistance of a walker. During the service, Siegel wrapped her hand in Kopelov’s hand and they both grasped the walker.

Witnesses cheered and wiped away tears after the two women vowed to honor and cherish each other as spouses and then kissed.

“I am breathless. I almost couldn’t breathe,” Siegel said after the ceremony. “It’s mind-boggling. The fact that it’s happening to us — that we are finally legal and can do this like everyone else.”

New York’s adoption of legal same-sex marriage is viewed as a pivotal moment in the national gay rights movement. The state joined Connecticut, Iowa, Massachusetts, New Hampshire and Vermont, along with Washington, D.C., when it voted last month to legalize gay marriage.