The districts that contain Chicago, Los Angeles and New York City ranked last in terms of federal gun law enforcement in 2012, according to a new report from Syracuse University's Transactional Records Access Clearinghouse, which tracks federal data. Federal gun crimes include illegal possession of a firearm in a school zone, illegal sale of a firearm to a juvenile, felon, or drug addict, and illegal transport of a firearm across state lines. In Chicago, the majority of gun charges last year were for firearms violations.