Which amendment to the U.S. Constitution abolished slavery in 1865?

The amendment to the U.S. Constitution that abolished slavery in 1865 was the Thirteenth Amendment.

Congress passed the Thirteenth Amendment on January 31, 1865, and the required three-fourths of the states ratified it on December 6, 1865. Its first section abolished slavery and involuntary servitude throughout the United States, except as punishment for a crime after conviction.

President Abraham Lincoln had issued the Emancipation Proclamation in 1863, but that wartime measure applied mainly to enslaved people in areas rebelling against the Union. The Thirteenth Amendment created a permanent constitutional prohibition that applied nationwide. It also addressed slavery in the border states and in territories not covered by the proclamation.

The amendment did not by itself guarantee equal citizenship or voting rights. The Fourteenth Amendment, ratified in 1868, addressed citizenship and equal protection, while the Fifteenth Amendment, ratified in 1870, addressed voting rights for men regardless of race. Enforcement of the Thirteenth Amendment remains part of the Constitution's text.