Juneteenth, also known as Freedom Day, Jubilee Day and Cel-Liberation Day, is an American holiday celebrated today, June 19, to commemorates the effective end of slavery in the United States.

Juneteenth (short for “June Nineteenth”) marks the day when federal troops arrived in Galveston, Texas in 1865 to take control of the state and ensure that all enslaved people be freed. The troops’ arrival came a full two and a half years after the signing of the Emancipation Proclamation. Juneteenth honors the end to slavery in the United States and is considered the longest-running African American holiday.

The Emancipation Proclamation issued by President Abraham Lincoln on January 1, 1863, had established that all enslaved people in Confederate states in rebellion against the Union “shall be then, thenceforward, and forever free.” But in reality, the Emancipation Proclamation didn’t instantly free any slaves. The proclamation only applied to places under Confederate control and not to slave-holding border states or rebel areas already under Union control. However, as Northern troops advanced into the Confederate South, many slaves fled behind Union lines.

After the war came to a close that spring of 1865, General Granger’s arrival in Galveston, Texas that June signaled freedom for Texas’s 250,000 slaves. Although emancipation didn’t happen overnight for everyone—in some cases, slave owners withheld the information until after harvest season—celebrations broke out among newly freed black people, and Juneteenth was born. **That December, slavery in America was formally abolished with the adoption of the 13th Amendment. “It is my greatest and most enduring contribution to the history of the war,” Lincoln said of emancipation in February 1865, two months before his assassination. “It is, in fact, the central act of my administration, and the great event of the 19th century.” How will you be celebrating this historical day?