Juneteenth is a federal holiday in the United States commemorating the emancipation of enslaved African Americans. Juneteenth marks the anniversary of General Order No. 3 by Major General Gordon Granger on June 19, 1865, proclaiming freedom for slaves in Texas. Originating in Galveston, the holiday has since been observed annually on June 19 in various parts of the United States, often broadly celebrating African-American culture. The day was first recognized as a federal holiday on June 17, 2021, when President Joe Biden signed the Juneteenth National Independence Day Act into law after the efforts of Lula Briggs Galloway, Opal Lee, and others.

Early celebrations date to 1866, at first involving church-centered community gatherings in Texas. They spread across the South and became more commercialized in the 1920s and 1930s, often centering on a food festival. Participants in the Great Migration brought these celebrations to the rest of the country. During the Civil Rights Movement of the 1960s, these celebrations were eclipsed by the nonviolent determination to achieve civil rights, but grew in popularity again in the 1970s with a focus on African American freedom and African-American arts. Beginning with Texas by proclamation in 1938, and by legislation in 1979, every U.S. state and the District of Columbia has formally recognized the holiday in some way. With its adoption in parts of Mexico, the holiday has become an international holiday. Juneteenth is celebrated by the Mascogos, descendants of Black Seminoles who escaped from slavery in 1852 and settled in Coahuila, Mexico.

Celebratory traditions often include public readings of the Emancipation Proclamation, singing traditional songs such as "Swing Low, Sweet Chariot" and "Lift Every Voice and Sing", and the reading of works by noted African-American writers, such as Ralph Ellison and Maya Angelou. Juneteenth celebrations may also include rodeos, street fairs, cookouts, family reunions, parties, historical reenactments, and Miss Juneteenth contests. In 2021, Juneteenth became the first new federal holiday since Martin Luther King Jr. Day was adopted in 1983.