Uniform Crime Reports County Data
This collection consists of four county-level data files. The first three provide arrests for Part I offenses (murder, rape, robbery, assault, burglary, larceny, auto theft, and arson) and for Part II offenses (forgery, fraud, embezzlement, vandalism, weapons violations, sex offenses, drug and alcohol abuse violations, gambling, vagrancy, curfew violations, and runaways). The fourth file provides reported offenses (as opposed to arrests) for Part I crimes only. Two county population variables are included : one for total county population and the other for counties reporting six months or more of data.
Data collected by the United States Department of Justice - Federal Bureau of Investigation. The data used in this presentation were obtained via anonymous ftp from the National Archive of Criminal Justice Data.
Other crime data is available in spreadsheet and interactive format from the Bureau of Justice Statistics, including state-level data.
Data last updated September 2004
NOTE ON POPULATION ESTIMATES:
The population estimates provided in these files should not be treated as an absolute population count. These data are built from agency-level records which are combined to form county estimates. Because not all agencies report data, the population represented by a non-reporting agency is not available for aggregation into the county population total. County population figures may vary between the arrests and crimes files in a given year as well. This is due to differences in the completeness of the reporting of arrests and crimes.
NOTE ON 1994 CHANGE IN METHODOLOGY:
Two major changes to the UCR county-level files were implemented with the 1994 release data. A new imputation algorithm to adjust for incomplete reporting by individual law enforcement jurisdictions has been adopted. Also, a new Coverage Indicator has been created to provide users with a diagnostic measure of aggregated data quality in a particular county. These developments are described in greater detail below. The changes have been instituted in response to comments from a number of users and after almost a year of discussions by UCR file users, the Uniform Crime Reports Unit of the Federal Bureau of Investigation, the Bureau of Justice Statistics, and the Inter-university Consortium for Political and Social Research. These changes will result in a break in series from previous UCR county-level files. Consequently data from earlier year files should not be compared to data from 1994 and subsequent years because changes in procedures used to adjust for incomplete reporting at the ORI or jurisdiction level may be expected to have an impact on aggregates for counties in which some ORIs have not reported for all 12 months. However, the new adjustment procedures should result in county-level data that are less sensitive to changes between years in the extent of reporting by ORIs within a county and consequently data from 1994 forward should be more useful for longitudinal analysis.