Welcome U.S. History Students!!! Today you will be exploring the history of U.S. Prohibition of Alcohol. The prohibition of alcohol, 1920-1933, is one of the most interesting policy experiments in U.S. history. Temperance movements waxed and waned in the U.S. from early in the nineteenth century, and these movements produced numerous state prohibitions. Many of these prohibitions were subsequently repealed, however, and those that persisted were widely regarded as ineffective. Amid the atmosphere created by World War I, support for national prohibition reached critical mass, and the country ratified the 18th Amendment to the Constitution in January, 1919. Under this amendment and the Volstead Act, which provided for the enforcement of Prohibition, the manufacture, transportation, and sale of alcohol were prohibited by federal law. The Amendment was popular for many years, but beginning in the late 1920s support began to erode. In 1933 the 21st Amendment repealed the 18th, ending Prohibition.