United States Constitution (Image Courtesy of the National Archives)
Answer: The 21st Amendment, ratified on December 5, 1933, repealed the 18th Amendment and with it the federal Prohibition of alcohol. (The Amendment gave the states extensive authority to regulate alcoholic beverages.)
The eighteenth article of amendment to the Constitution of the United States is hereby repealed.
The transportation or importation into any state, territory, or possession of the United States for delivery or use therein of intoxicating liquors, in violation of the laws thereof, is hereby prohibited.
This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by conventions in the several states, as provided in the Constitution, within seven years from the date of the submission hereof to the states by the Congress.
Source: Legal Information Institute: Cornell University Law School
The 21st Amendment is unique among amendments because it was the only one that overturned an existing Amendment and the only one ratified by state ratifying conventions rather than state legislatures. These statewide conventions were specially elected for that purpose, according to Linda Monk in The Words We Live By. Adds Monk:
“Approximately seventy-three percent of the twenty-one million citizens who voted in those elections supported the Twenty-first Amendment.” (The Words We Live By, page 248)
The 18th Amendment (Text) had taken effect on January 17, 1920 and the prohibition of alcohol was widely blamed for creating widespread corruption and organized crime, ultimately leading to its repeal.
An excellent history of the Prohibition period is Last Call: The Rise and Fall of Prohibition by Daniel Okrent.
You can also read more about the Prohibition era in Don’t Know Much About History.
Don’t Know Much About® History: Anniversary Edition (Harper Perennial and Random House Audio)