President Abraham Lincoln's Emancipation Proclamation issued on 1 January 1863 had officially outlawed slavery in Texas and in all of the other states of the original Confederacy. Enforcement of the Proclamation generally relied upon the advance of Union troops. Texas, as the most remote state of the former Confederacy, had seen an expansion of slavery and had a low presence of Union troops as the American Civil War ended; thus, enforcement there had been slow and inconsistent prior to Granger's announcement.
Celebrations date to 1866, at first involving church-centered community gatherings in Texas. It spread across the South and became more commercialized in the 1920s and 1930s, often centering on a food festival. Participants in the Great Migration out of the South carried their celebrations to other parts 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, 49 U.S. states and the District of Columbia have formally recognized the holiday in various ways. With its adoption in certain parts of Mexico, the holiday became 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. Some Juneteenth celebrations also include rodeos, street fairs, cookouts, family reunions, park parties, historical reenactments, and Miss Juneteenth contests. On June 15, 2021 Juneteenth became a federal holiday with the passage of the Juneteenth National Independence Day Act, which was signed into law on June 17, 2021. Juneteenth is the first new federal holiday since Martin Luther King Jr. Day was declared a holiday in 1983.