Impact of World War I, immigration, prohibition, gangs. The Mafia.
“World War I impacted the spread and organization of organized crime in two major ways. First, the immigrant push out of Europe following the devastation of the war meant the concentration of large numbers of immigrants in New York and other large American cities in the early twentieth century. In particular, such immigrants included people who affiliated themselves with the Sicilian Mafia, who would play a significant role in the development of organized crime in the 1920s. The second impact followed the decision by the United States Congress to pass the Volstead Act in 1920, which prohibited the manufacture or sale of alcohol in the United States. This event, which coincided with the return of U.S. troops and a general feeling of …”