Speakers included U.S. Reps.
People participate in a Resist March that replaced the annual Pride Parade in Los Angeles, California, June 11.
Damian Jessup, 30, who travelled from Norfolk, Virginia, to march with gay Republicans, defended Trump and his support for gays.
Mayor Eric Garcetti also spoke, as did City Council member Mitch O'Farrell, who called Trump an "authoritarian", and listed the president's alleged crimes, provoking the crowd to chant: "Lock him up!"
"We need to be out here to tell people that God loves them for who they are and who they love", said the Rev. Alex Dyer, 38, an Episcopal priest from Washington who marched in the parade with his husband and 2-year-old daughter.
"You're not going to make everybody happy and unfortunately there are a couple of people that were upset", said Papadatos.
"It's unfortunate that we've got several hundred thousand people that are now not able to see the parade unless they are moved by the police, which kind of breaks my heart", Renna said. I know that you have the courage.
As for gay conservatives who might feel unwelcome: "I would hope they would be understanding and open-minded".
"That's why [Clark is] marching with the city councillors, to show that we are moving forward as a community to become an inclusive and diverse city", said Papadatos.More news: AAP demands Shivraj's scalp over MP farmers' deaths
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Back in Washington, the activist leaders on hand included Sarah Kate Ellis, president of GLAAD, which monitors media coverage of the LGBT community.
The change came as President Donald Trump failed to acknowledge June as Pride month in the USA, opting not to issue a statement in support of the LGBTQ community as his predecessor Barack Obama had done.
"If you look at their prioritization, we're really low on it, " she said. "This was the year to take to the streets and march", Stephen Macias, a spokesman for the organizers, told Reuters.
The annual global Pride celebrations in June, which attract hundreds of thousands of people in cities worldwide, can be traced back to a more modest and decorous demonstration organized in Philadelphia in 1967.
A few dozen people attended the "Annual Reminder" demonstration each year.
Kameny, who held a Harvard doctorate and lived in the nation's capital until his death in 2011, was ousted from his federal government job in 1957 because of his homosexuality.
"We are honoured and deeply humbled to accept the invitation of Grand Marshal for the Pride Parade", Boyd Whiskeyjack, Two-Spirit co-ordinator with the Edmonton Pride Centre, said in a news release.
In the 1960s, Kameny's message was always more about having gays and lesbians be accepted in the eyes of the law rather than a more edgy "gay power" message.