Which constitutional amendment abolished slavery?
Because the 1863 Emancipation Proclamation did not end slavery throughout the United States, only in some Confederate states, President Abraham Lincoln and abolitionists lobbied for a constitutional amendment abolishing slavery nationwide. The 13th Amendment passed Congress in January 1865, and it was ratified that December. It freed 4 million Black Americans, but has been criticized for a loophole allowing involuntary servitude for those convicted of a crime, which has been linked to racially unequal incarceration rates and the penal labor system.
Source: History.com