Prohibition is the term applied to a policy by the US government, as well as the era it occurred in, banning the transport or sale of alcohol across state lines. While the federal government failed to garner the support it needed for a total ban on liquor in the form of an actual law or constitutional amendment, it agreed to regulate the transport of alcohol across state lines by making it strictly forbidden and soon thereafter deeming all liquor production to fall under their powers in the "commerce clause."
Prohibition has been deemed a disaster by most historians, as it helped give rise to bootleggers such as the Bogart outfit in Chicago, the rise of the Italian mob (in particular in New York and Philadelphia), the growth of the already-powerful Irish, Russian and Jewish criminal organizations across the country, and led to the growth of black gangs modelling their business styles on Northeastern and Midwestern gangs in Covenant, Atlanta and New Orleans. It also showed the inability of the federal government to enforce such a sweeping law, brought the government to a head with states, in particular "wet" states that legalized alcohol, and added one more thorny problem for the US government on top of the ongoing Pacific War and deep recession that lasted the majority of the 1920's. Prohibition was finally repealed in 1932.