Just days before the parade, President Obama designated America's first LGBT national monument at the city's Stonewall Inn, where protests known as the Stonewall Uprising erupted in 1969 following a police crackdown.
Hundreds of thousands of Americans took to streets from New York to San Francisco to celebrate gay pride, honour those who died in the Orlando massacre and promote tolerance.
Democratic presidential candidate Hillary Clinton, buoyed by a double-digit poll lead over Republican Donald Trump in the race for the White House, joined the tail end of the route on Sunday in New York.
In San Francisco, the crowd cheered and electronic music blared from floats, a group carried placards with photos of the Orlando victims and men in leather bondage walked the route under bright sunshine.
Clinton tweeted:
She was referring to the US Supreme Court decision a year ago to legalise gay marriage across the country. New York, which prides itself on being one of the most diverse cities on the planet, is the birthplace of the gay rights movement.
Just days before the parade, President Barack Obama designated America's first LGBT national monument at the city's Stonewall Inn, where protests that came to be known as the Stonewall Uprising erupted in 1969 following a police crackdown. At the same spot, once synonymous with law enforcement brutality, a uniformed police band with "Happy Pride Day" signs played "God Bless America" to cheers.
The US events, also in Chicago and Seattle, were a celebration but also a tribute to the 49 people killed at a gay nightclub on June 12 in America's single worst mass shooting, which has once again inflamed calls for gun control.
"We have extraordinary NYPD presence to make sure that this will not only be the biggest but the safest parade we've ever had," said Mayor Bill de Blasio before the first march kicked off in New York with a moment of silence. "We will stand up to hatred. We will stand up to those who would try to undermine our values. We believe in a society for everyone. And I have to say the response has been amazing," he added.
Scouts carried 49 flags with rainbow stripes to honour the victims, a group was dressed head-to-toe in white and wore veils, with placards with the names and photographs of the Orlando dead hanging around their necks.
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 "People march and wave flags during San Franciscos Gay Pride parade in California on June 26, 2016.")
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