Before Stonewall, there was already a fight
The popular story starts at Stonewall in 1969. The real one starts earlier. Through the 1950s and 60s, simply being gay, lesbian, or transgender could cost you your job, your home, your freedom, or your safety. Same-sex intimacy was criminalized across most of the United States, and police raids on the few bars and gathering places that welcomed queer people were routine.
Against that, the earliest organized movement took shape. The Mattachine Society, founded in Los Angeles in 1950, and the Daughters of Bilitis, founded in San Francisco in 1955, were among the first sustained advocacy groups for gay and lesbian people in the country. Historians call this the "homophile" era: cautious, careful, and dangerous to be part of at all.
Compton's Cafeteria, 1966
Three years before Stonewall, transgender women and drag queens in San Francisco's Tenderloin district fought back against police harassment at Compton's Cafeteria. It is one of the earliest documented instances of LGBTQ+ people physically resisting police in the United States. The people at the center of it were trans women, often poor, often turned away everywhere else.
Sources: GLBT Historical Society; Library of Congress LGBTQ+ history collections. Exact date in August 1966 is not firmly established in the record.