The Eighteenth Amendment (Amendment XVIII) to the United States Constitution established the prohibition of alcohol in the United States. The amendment was proposed by Congress on December 18, 1917, and ratified by the requisite number of states on January 16, 1919. The Eighteenth Amendment was repealed by the Twenty-first Amendment on December 5, 1933—it is the only constitutional amendment in American history to be repealed.

The Eighteenth Amendment was the product of decades of efforts by the temperance movement, which held that a ban on the sale of alcohol would ameliorate poverty and other societal problems. The Eighteenth Amendment declared the production, transport and sale of intoxicating liquors illegal, although it did not outlaw the actual consumption of alcohol. Shortly after the amendment was ratified, Congress passed the Volstead Act to provide for the federal enforcement of Prohibition. The Volstead Act declared that liquor, wine and beer qualified as intoxicating liquors, and were therefore prohibited. Under the terms of the Eighteenth Amendment, Prohibition began on January 17, 1920, one year after the amendment was ratified.

Although the Eighteenth Amendment led to a decline in alcohol consumption in the United States, nationwide enforcement of Prohibition proved difficult, particularly in cities. Alcohol smuggling (known as rum-running or bootlegging) and illicit bars (speakeasies) became popular in many areas. Public sentiment began to turn against Prohibition during the 1920s, and 1932 Democratic presidential nominee Franklin D. Roosevelt called for its repeal.

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Section 1. After one year from the ratification of this article the manufacture, sale, or transportation of intoxicating liquors within, the importation thereof into, or the exportation thereof from the United States and all territory subject to the jurisdiction thereof for beverage purposes is hereby prohibited.

Section 2. The Congress and the several States shall have concurrent power to enforce this article by appropriate legislation.

Section 3. This article shall be inoperative unless it shall have been ratified as an amendment to the Constitution by the legislatures of the several States, as provided in the Constitution, within seven years from the date of the submission hereof to the States by the Congress.

The amendment was proposed by the 62nd Congress in 1912 and became part of the Constitution on April 8, 1913, on ratification by three-quarters (36) of the state legislatures. Sitting senators were not affected until their existing terms expired. The transition began with two special elections in Georgia[1] and in Maryland, then in earnest with the November 1914 election; it was complete on March 4, 1919, when the senators chosen by the November 1918 election took office.

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The Senate of the United States shall be composed of two Senators from each State, elected by the people thereof, for six years; and each Senator shall have one vote. The electors in each State shall have the qualifications requisite for electors of the most numerous branch of the State legislatures.

When vacancies happen in the representation of any State in the Senate, the executive authority of such State shall issue writs of election to fill such vacancies: Provided, That the legislature of any State may empower the executive thereof to make temporary appointments until the people fill the vacancies by election as the legislature may direct.

This amendment shall not be so construed as to affect the election or term of any Senator chosen before it becomes valid as part of the Constitution.[2]