October is LGBT History Month here in the United States, home to the Stonewall Riots of 1969 and the Mattachine Society, one of the earliest gay organizations.

The country has a rich background concerning the LGBT community that remains in the shadows. In celebration of all the figures who fought for the rights of themselves and others, here are major events in LGBT history.

The Formation of the Mattachine Society

Founded in 1950 by Harry Hay, this homophile organization is the second ever in the United States, right behind Chicago’s Society for Human Rights. Its format paralleled the Communist Party of the United States, which didn’t help when it was investigated by the FBI between 1953 and ‘56. Members of the Mattachine Society worked to present themselves respectfully and humbly in hopes of gaining more acceptance in mainstream society. Though it declined and fractionated itself only 11 years later, the society broke boundaries for the LGBT community.

The Stonewall Riots

Greenwich Village of New York City was thick with tension in the midsummer of 1969. The Stonewall Inn, a popular club for gay men and transgender women, was raided regularly by police, and patrons were routinely arrested for violating city clothing laws dictating what men and women were supposed to wear. One raid broke out into violence on June 28 with the leadership of Marsha P. Johnson and Sylvia Rivera, two trans women of color. The two-day riot is considered to be the beginning of the gay rights movement in the U.S. and in June of 2016, President Barack Obama declared the Inn a national monument.

Creation of the Pride Flag

Gilbert Baker, a Kansas native, was asked by popular gay rights activist and politician Harvey Milk to create a symbol of pride for the gay community. The infamous pride flag flew at the San Francisco Gay Freedom Day Parade on June 25, 1978. Originally, it included eight stripes, with hot pink, indigo and turquoise, but was changed after the assassination of Harvey Milk. The official colors are red (life), orange (healing), yellow (sunlight), green (nature), blue (serenity) and violet (spirit).

First Openly LGBT Official to be Federally Appointed

In 1993, Roberta Achtenberg was elected to be an assistant secretary for fair housing and equal opportunity for the Department of Housing and Urban Development. She was chosen with approval by the U.S. Senate, and became a commissioner for the United States Commission on Civil Rights in 2011. Prior to this, she was a civil rights attorney and co-founded the National Center for Lesbian Rights.

Obergefell v. Hodges

Six lower-court cases from across the United States culminated to create the landmark Supreme Court case that legalized same-sex marriage in every state. On June 26, 2015, the justices announced their majority opinion that cited the due process and equal protection clause of the Fourteenth Amendment. As of 2015, same-sex marriage is legal nationwide.