Crowds gathered near public buildings in small communities and major cities including New York, San Francisco and Chicago to vent their frustrations, celebrate gay relationships and renew calls for change.
"Civil marriages are a civil right, and we're going to keep fighting until we get the rights we deserve as American citizens," Karen Amico said in Philadelphia, holding up a sign reading "Don't Spread H8".
"We are the American family, we live next door to you, we teach your children, we take care of your elderly," said Heather Baker a special education teacher from Boston who addressed the crowd at Boston's City Hall Plaza. "We need equal rights across the country."
In Salt Lake City, rallies were planned at the Salt Lake City-County Building on Washington Square. A candlelight vigil was also scheduled at 6 p.m. on the south lawn of the state Capitol.
Massachusetts and Connecticut, which began same sex weddings this past week, are the only two states that allow gay marriage. All 30 states that have voted on gay marriage have enacted bans.
Protests following the vote on Proposition 8 in California, which defined marriage as between a man and a woman, have sometimes been angry and even violent, and demonstrators have targeted faiths that supported the ban, including the The Church of Jesus Christ of Latter-Day Saints.
However, representatives of Join the Impact, which organized Saturday's demonstrations, asked supporters to be respectful and refrain from attacking other groups during the rallies.
The mood in Boston was generally upbeat, with attendees dancing and signing to the song "Respect." Signs cast the fight for gay marriage as the new civil rights movement, including one that read "Gay is the new black."
But anger over the ban and its backers was evident at the protests.
One sign in Chicago read: "Catholic Fascists Stay Out of Politics."
"I just found out that my state doesn't really think I'm a person," said Rose Aplustill, 21, a Boston University student from Los Osos, Calif., who was one of thousands at the Boston rally.
Planning for the nationwide protests was started by a Seattle blogger, Amy Balliett, just days after the California vote, which took away gay marriage rights that had been granted by the state's high court.
The idea rapidly spread online and Join the Impact predicted that Saturday's protests would involve tens of thousands of people in hundreds of communities.
In North Dakota, where voters in 2004 overwhelmingly approved a constitutional ban on same-sex marriage, low-key protests were held Saturday in Grand Forks and Fargo, where people lined a bridge carrying signs and flags.
"It's been very peaceful," said Josh Boschee, who helped organize the Fargo protest.
In Chicago, Keith Smith, 42, a postal worker, and his partner, Terry Romo, 34, a Wal-Mart store manager, had photos of their wedding ceremony which they held even though gay marriage is not legal in Illinois.
"We're not going to wait for no law," Smith said. "But time's going to be on our side and it's going to change."
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