The document that abolished slavery in the United States is the 13th Amendment to the Constitution, ratified in December 1865. This amendment formally ended the practice of slavery and involuntary servitude, except as punishment for a crime. It was a significant milestone in the American Civil War, which had been fought, in part, over the issue of slavery. The amendment's passage marked a pivotal moment in U.S. history, as it fundamentally changed the social, economic, and political landscape of the nation, and laid the groundwork for subsequent civil rights advancements.