"The Uniform Crime Reporting Program is a nationwide, cooperative statistical effort of more than 17,000 city, county, and state law enforcement agencies voluntarily reporting data on crimes brought to their attention. During 2002, law enforcement agencies active in the UCR Program represented 93.4 percent of the total population as established by the Bureau of Census. The coverage amounted to 94.3 percent of the United States population in Metropolitan Statistical Areas (MSAs), 89.9 percent of the population in cities outside metropolitan areas, and 89.5 percent in rural counties. Since 1930, the FBI has administered the Uniform Crime Reporting Program and issued periodic assessments of the nature and type of crime in the Nation. The Program's primary objective is to generate a reliable set of criminal statistics for use in law enforcement administration, operation, and management; however, its data have over the years become one of the country's leading social indicators. The American public looks to Uniform Crime Reports for information on fluctuations in the level of crime, and criminologists, sociologists, legislators, municipal planners, the media, and other students of criminal justice use the statistics for varied research and planning purposes. Recognizing a need for national crime statistics, the International Association of Chiefs of Police (IACP) formed the Committee on Uniform Crime Records in the 1920s to develop a system of uniform police statistics."
Federal Bureau of Investigation: http://www.fbi.gov/