Chicago
The ratification of the 18th amendment to the Constitution in 1919 made the production and sale (including exportation) of alcoholic beverages illegal in the United States. This ushered in the beginning of what is known as the Gangster Era, a time that roughly spans from 1919 until 1933 when Prohibition was repealed. The 1920s saw gangsters, including Al Capone, Dion O'Banion, Bugs Moran and Tony Accardo battle law enforcement and each other on the streets of Chicago during the Prohibition era. Chicago was the location of the infamous St. Valentine's Day Massacre in 1929, when Al Capone sent men to gun down members of a rival gang, North Side, led by Bugs Moran.
Progressive Era
By 1917, two thirds of the states had some form of prohibition laws and roughly three quarters of the population lived in dry areas. In 1913, the Anti-Saloon League first publicly appealed for a prohibition amendment. They preferred a constitutional amendment over a federal statute because although harder to achieve, they felt it would be harder to change. As the United States entered World War I, the Conscription Act banned the sale of liquor near military bases. In August 1917, the Lever Food and Fuel Control Act banned production of distilled spirits for the duration of the war. The War Prohibition Act, November, 1918, forbade the manufacture and sale of intoxicating beverages (more than 2.75% alcohol content) until the end of demobilization.