Juneteenth marks the official end of slavery in the U.S. The original legal declaration was signed into law by Abraham Lincoln which instituted Emancipation Proclamation. Juneteenth is the oldest known celebration honoring the end of slavery in the United States. On June 19, 1865, Union General Gordon Granger led thousands of federal troops to Galveston, Texas to announce that the Civil War had ended, and slaves had been freed.