In the 1960s, Compton's Cafeteria in San Francisco's gritty Tenderloin neighborhood was virtually the only place in the city where transgender folks could congregate publicly, as they weren't allowed in gay bars at the time. Cross-dressing was still illegal in the city, and the local police often used the presence of trans women as a pretext for raiding and closing gay bars.
The patrons at Compton's were used to being rousted by the police, but one night, after a cop attempted to arrest one trans woman, that "street queen" (as the women were often called) fought back and tossed her drink into the officer's face. A huge riot broke out and spilled into the neighborhood, becoming one of the first transgender uprisings in the U.S., three years before New York's Stonewall. (There was a much smaller riot in L.A. in 1959.)
Trans people weren't the only ones rioting as the hours went on; they were joined by many from the country's first youth group, Vanguard Youth, as well as numerous street dykes, queer hustlers, and neighborhood locals. Later LGBT folks from other parts of the city joined in.
The Compton's riot was a turning point in trans liberation, and by 1969 the first transgender advocacy group in the nation -- and the world -- had been founded, according to GLBTQ.com.