The celebration began early and built throughout the day in San Francisco, a city at the vanguard of the gay rights fight.
Workers draped a giant, one-story-long rainbow flag over the front door of City Hall minutes after the U.S. Supreme Court legalized gay marriage nationwide on Friday morning. Three hours later, the dozens of same-sex marriage backers who initially showed up grew to more than 1,000 cheering supporters standing in front of City Hall.
That's where then-Mayor Gavin Newsom ignited a legal challenge to California's same-sex marriage ban 11 years ago when he ordered clerks to marry a gay couple in defiance of state law.
The California Supreme Court legalized gay marriage in 2013 after several legal setbacks, including the passage of Proposition 8, which briefly banned same-sex weddings in the state.
Newsom is now California's lieutenant governor and told the crowd Friday that San Francisco celebrates diversity.
Afterward, at an impromptu press conference, he reminisced about that Valentine's Day 11 years ago when he hoped that his action would spark a legal challenge. It did that - and more. A sympathetic state court declined to stop San Francisco's City Hall from issuing marriage licenses for more than a month afterward and hundreds of same-sex couples flocked to the city to marry.
"We were hoping to humanize the issue,'' Newsom said of the first marriage performed at City Hall on Feb. 14, 2004. "What none of us expected is that the courts would allow us to continue marrying gay couples.''
Newsom said "I'm proud I didn't wait around for the 'right time' to marry same-sex couples,'' but that he couldn't imagine then that gay marriage would be legalized nationwide.
"I'd like to say I expected this day,'' Newsom said. ``I didn't. We hit a lot of rough patches along the way.''
A small number of same-sex marriage opponents protested the Supreme Court decision by unfurling a banner on a freeway overpass across the San Francisco Bay in Berkeley.
San Francisco was already primed for its annual Gay Pride weekend, a raucous 48 hours of parties and same-sex weddings capped off by a parade attended by tens of thousands. Rainbow flags hung from lampposts along the planned parade route and workers were erecting scaffolding and stages in front of City Hall in preparation for the weekend's events.
Mark Streeter and Hai Nguyen just happened to schedule their City Hall wedding for Friday morning and were besieged by well-wishers and media, granting several television interviews before tying the knot.
"This is surreal,'' said Streeter. ``It was the last appointment slot they had left when I called to reserve a spot.''
Streeter's beaming mother traveled from Georgia for the wedding.
"It's providential,'' she said of the timing of the wedding.
San Francisco Mayor Ed Lee told the throng that the city has "always been proud in our role leading the nation, perhaps the world'' in fighting for gay rights in general and same-sex marriage in particular.