The Eighteenth Amendment to the U.S. Constitution was ratified in the state of Illinois in 1919.
Prohibition built the reputation of Al Capone who became the country's best known gangster. It also cemented Chicago's reputation as a city of crime and violence in the late 1920s, with the St. Valentine's Day Massacre of 1929.
Links for Prohibition Days in Chicago:
"Prohibition and Temperance (1920-1933)" from Homicide in Chicago pages (Northwestern University).
"Prohibition and Temperance," Encyclopedia of Chicago Entry (2005).
"Prohibition: Its Effects on Chicagoans and Organized Crime," student project (University of Michigan).
Links to the 75th anniversary of the Repeal of Prohibition:
Allen Katz, "Now Toasting: Happy Repeal Day!" The Moment from the New York Times (December 5, 2008).
Guy Tridgell, "Repeal Day: 75 years past Prohibition," SouthtownStar (December 5, 2008).
Radley Balko, "The Lessons of Prohibition: Repeal Day drives home the folly of the Drug War," Reason Online (December 3, 2008).
"Repeal Day is December 5th" by Jeffrey Morgenthaler (repealday.org).