In 1994, a coalition of education-based organizations in the United States designated October as LGBT History Month. In 1995, a resolution passed by the General Assembly of the National Education Association included LGBT History Month within a list of commemorative months. National Coming Out Day (October 11), as well as the first "March on Washington" in 1979, are commemorated in the LGBTQ community during LGBT History Month.
Reference: Library of Congress (2021) Lesbian, Gay, Bisexual, Transgender and Queer Pride Month. https://www.loc.gov/lgbt-pride-month/about/
Why Do We Celebrate Pride Month in June and LGBT History Month in October?
Library of Congress. (1970, June 28). Gay and proud. [Video]. Youtube. https://www.loc.gov/item/mbrs01991430/?