Thirteenth Amendment, amendment (1865) to the Constitution of the United States that formally abolished slavery. Although the words slavery and slave are never mentioned in the Constitution, the Thirteenth Amendment abrogated those sections of the Constitution which had tacitly codified the “peculiar institution”: Article I, Section 2, regarding apportionment of representation in the House of Representatives, which had been “determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons provided for the appointment,” with “all other persons” meaning slaves; Article I, Section 9, which had established 1807 as the end date for the importation of slaves, referred to in this case as “such Persons as any of the States now existing shall think proper to admit”; and Article IV, Section 2, which mandated the return to their owners of fugitive slaves, here defined as persons “held to Service or Labour in one State, under the Laws thereof, escaping into another.”

The Thirteenth Amendment to the Constitution of the United States of America. NARA

The Emancipation Proclamation, declared and promulgated by Pres. Abraham Lincoln in 1863 during the American Civil War, freed only those slaves held in the Confederate States of America. In depriving the South of its greatest economic resource—abundant free human labour—Lincoln’s proclamation was intended primarily as an instrument of military strategy. Only when emancipation was universally proposed through the Thirteenth Amendment did it become national policy. Moreover, the legality of abolition by presidential edict was questionable.

The full text of the amendment is:

Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction. Congress shall have power to enforce this article by appropriate legislation.

The amendment was passed by the Senate on April 8, 1864, but did not pass in the House until January 31, 1865. The joint resolution of both bodies that submitted the amendment to the states for approval was signed by Lincoln on February 1, 1865. However, he did not live to see its ratification. Assassinated by John Wilkes Booth, he died on April 15, 1865, and the amendment was not ratified by the required number of states until December 6, 1865.