Violent-crime rates are near historic lows in the United States, but in many urban areas violent crime, particularly homicide, remains pervasive, largely due to street gangs. In some areas police blame 80 percent of all crime on gangs. This summer, during a single weekend in Chicago, 54 people were shot, nearly all because of gang violence. Meanwhile, spillover from Mexico's violent narcotics trade is swamping U.S. law enforcement resources. The federal government estimates the U.S. gang population at 1 million, distributed across some 20,000 gangs. As the gangs grow larger, they merge and grow in strength, often overwhelming local and state police efforts. And a new study calls federal anti-gang efforts uncoordinated and ineffective. Meanwhile, though studies have shown that prevention and counseling programs provide a greater return on public investments than crime-fighting efforts, police anti-gang efforts still get far greater financial support.