An early 1990s report from the California Department of Justice noted that there were more than 500 U.S.-based motorcycle gangs at the time, many with evocative names like Iron Horsemen, Rebel Rousers ...

The founder of a California motorcycle gang tied to the Hells Angels pleaded guilty to federal firearms charges after authorities caught him allegedly trying to sell weapons to an undercover officer.

Law enforcement agencies estimate that tens of thousands of gangs operate across the United States today. These groups range from street gangs and prison gangs to organized criminal networks.