Between 1993 and 1994, the violent crime rate fell by 10 percent or more in 8 of 10 U.S. cities with the highest violent crime rates. New York City and Houston experienced significant declines in serious crimes, including murder. During 1995, the overall crime rate was down by more than 16 percent in San Francisco, by 10 percent in San Antonio, and by 6 percent in both Los Angeles and Philadelphia. In many cities, reduced crime rates can be explained at least in part by law enforcement efforts that capitalize on community crime fighting initiatives. Reduced crime rates are also attributed to sentencing policies that keep violent and repeat criminals behind bars. The author believes effective crime prevention should focus on hardening targets, tough and consistent treatment of offenders, and effective resource use. He refers to a "demographic time bomb" as the significant number of young males under 25 years of age who are responsible for much of the serious crime in the United States.