In Chicago, as many as 1 million people were expected to pack the streets of the city's North Side for the first gay pride parade since Illinois legalized gay marriage last month.
Charlie Gurion, who with David Wilk in February became the first couple in Cook County to get a same-sex marriage license, said there was a different feel to the parade this year.
"I think there is definitely like an even more sense of pride now knowing that in Illinois you can legally get married now," Gurion said, as he posed for photograph after photograph with Wilk at the parade. "I think it is a huge thing and everybody's over the moon that they can do it now."
In San Francisco, hundreds of motorcyclists of the lesbian group Dykes on Bikes took their traditional spot at the head of the 44th annual parade and loudly kicked off the festivities with a combined roar. Apple Inc. had one of the largest corporate presences, and chief executive Tim Cook greeted the estimated 4,000 employees and family members who participated.
U.S. House Minority Leader Nancy Pelosi, San Francisco Mayor Ed Lee and assorted state and local politicians rolled along Market Street along with gay city police officers holding hands with their significant others as their children skipped ahead.
For some veterans of the parade, the event has lost some its edge as it gains mainstream acceptance.
"There's less partying," said Larry Pettit, who said he attended the first parade more than four decades ago. "There's less sex. Everyone's interested in politics and no one is having sex."
A year ago, the U.S. Supreme Court issued a pair of landmark rulings, one striking down the statute that denied federal recognition to same-sex marriages and the other clearing the way for gay couples to wed legally in California.
In the 12 months since then, the ripple effects of those rulings has transformed the national debate over same-sex marriage, convincing many people on both sides of the contentious issue that its spread nationwide is inevitable.
From the East Coast to the Midwest and the Pacific, seven more states legalized same-sex marriage, boosting the total to 19, plus Washington, D.C. The Obama administration moved vigorously to extend federal benefits to married gay couples. And in 17 consecutive court decisions, federal and state judges have upheld the right of gays to marry. Not a single ruling has gone the other way.
Parades also were planned Sunday across the U.S., including in Minneapolis, Seattle and Houston. Humbler celebrations were being held in smaller towns and cities such as Augusta, Georgia, and Floyd, Virginia, while festivals were held Saturday in France, Spain, Mexico and Peru.
Among the marchers Sunday in New York were cousins Yaseena Oatis, 20, and Shayna Melendez, 22, from Plainfield, New Jersey.
"We're walking to celebrate, to be embraced being who we are around people who are like us, free to express ourselves," Oatis said. "Everybody has a different story about how they came out as gay, but we're all here."
Associated Press writer Don Babwin in Chicago and Paul Elias in San Francisco contributed to this report.