The Twenty-first Amendment (Amendment XXI) to the United States Constitution repealed the Eighteenth Amendment to the United States Constitution, which had mandated nationwide prohibition on alcohol. The Twenty-first Amendment was proposed by the 72nd Congress on February 20, 1933, and was ratified by the requisite number of states on December 5, 1933. It is unique among the 27 amendments of the U.S. Constitution for being the only one to repeal a prior amendment, as well as being the only amendment to have been ratified by state ratifying conventions.
The Eighteenth Amendment was ratified on January 16, 1919, after years of advocacy by the temperance movement. The subsequent enactment of the Volstead Act established federal enforcement of the nationwide prohibition on alcohol. As many Americans continued to drink despite the amendment, Prohibition gave rise to a profitable black market for alcohol, fueling the rise of organized crime. Throughout the 1920s, Americans increasingly came to see Prohibition as unenforceable, and a movement to repeal the Eighteenth Amendment grew until the Twenty-first Amendment was ratified in 1933.