The legal system in the US during the 1950s and 1960s was very anti-homosexual. Most establishments did not welcome openly gay people. The Mafia owned bar Stonewall Inn in the Greenwich Village neighborhood of New York City was the exception. Police raids were common at bars like that and homosexual felt harassed by the police.
A routine police raid at the Stonewall Inn on June 28, 1969 finally sparked a series of violent demonstrations by members of the gay community in Greenwich. These events are considered most important leading to the fight for gay and lesbian rights in the US.