Gangster, member of a criminal organization that systematically makes money from such activities as gambling, prostitution, narcotic trafficking, and industrial extortion. Although there exist throughout the world professional criminals that work with associates on a particular job or series of jobs, the gangster is a member of a permanent, highly structured organization. the gangster was formed during the Prohibition Era (1920–33), as the U.S. underworld battled over markets controlling the illegal manufacture and distribution of liquor. Gang murder became commonplace, especially in New York and Chicago, where more than 2,000 killings between 1920 and 1930 were ascribed to gang warfare. The manner as well as the number of these killings made them notorious. Usually they were carefully rehearsed and involved sophisticated techniques for stealing and disguising the “get-away” car; for obliterating all means of identification from the murder weapons; for luring the victim into a defenseless situation (as when one killer shook hands with the victim to prevent his reaching for a gun, while associates opened fire); and for disposing of the body, The most famous gang shooting was the Saint Valentine’s Day massacre in Chicago on February 14, 1929. Because such killings were carefully planned, and also because the criminals had influence with local political leaders, gang murderers were rarely identified, still less often prosecuted, and almost never convicted. In Chicago, for example, between 1927 and 1930 there were 227 killings and only two convictions.