Here’s the Wikipedia entry for Juneteenth:
Juneteenth (officially Juneteenth National Independence Day) is a federal holiday in the United States commemorating the emancipation of enslaved African Americans. Deriving its name from combining June and nineteenth, it is celebrated on the anniversary of the order by Major General Gordon Granger proclaiming freedom for enslaved people in Texas on June 19, 1865 (two and a half years after the Emancipation Proclamation was issued). Originating in Galveston, Juneteenth has since been observed annually in various parts of the United States, often broadly celebrating African-American culture. The day was first recognized as a federal holiday in 2021, when President Joe Biden signed the Juneteenth National Independence Day Act into law.