This fact sheet from the U.S. Department of Justice, Office of Juvenile Justice and Delinquency Prevention discusses the findings from the 2007 National Youth Gang Survey. "Following a marked decline from the mid 1990s to the early 2000s, a steady resurgence of gang problems has occurred in recent years. More than one third of the jurisdictions in the National Youth Gang Survey (NYGS) study population experienced gang problems in 2007, the highest annual estimate since before 2000. Within the four area types surveyed, 86 percent of law enforcement agencies that serve larger cities, 50 percent of agencies that serve suburban counties, 35 percent of agencies that serve smaller cities, and 15 percent of agencies that serve rural counties reported experiencing youth gang problems in 2007."
National Criminal Justuce Reference Service: http://www.ncjrs.gov/