PBS
Pbs: American Experience: Public Enemy #1: Gangsters During the Depression
"Gangsters" in the Great Depression were divided into two different groups: Mobsters and Outlaws. This article discusses the differences between the two and the role each group played.
Other
University at Albany: Organized Crime and Prohibition
Features statistics and details about organized crime and prohibition including facts on some of the more colorful gangsters during that era.
Chicago History Museum
Encyclopedia of Chicago: Al Capone
A brief historical account of infamous member of the Chicago's underworld, Alphonse Capone.
Other
Roaring 20s Gangster Links
Provides a list of links regarding the 1920s most famous gangsters, bootleggers, rumrunners, drug peddlers, and labor racketeers.