Chicago is the gang capital of the United States. According to the Chicago Crime Commission, a 2012 Chicago Police Department gang audit found there are more than 600 gang factions in the city, with a minimum combined membership of 70,000. As the number of gangs in the city increase, it's difficult for gangs to control large areas. Instead, gangs cling to streets. Territory disputes mean increased rivalry and as a result, more shootings.
In 2011, a quarter of the 433 homicides in Chicago were gang motivated according to the Chicago Police Murder Analysis; 83 percent of all homicide victims died as a result of shootings.
The Chicago Crime Commission and Chicago Police Department generally define a gang as a group of individuals with regular meeting patterns, have recognizable geographical territory (typically identified by graffiti), leadership structure, a stated purpose or manifesto, and various levels of an organized, continuous course of criminal activities.