"The United States has three national data resources that collect law enforcement employment statistics along with other information unique to each collection. The FBI, U.S. Census Bureau, and the Bureau of Justice Statistics (BJS) data collections programs have different purposes, data definitions, respondent universes, and data collection procedures. This report details the similarities and differences among these three collections and discusses when the use of one may be preferred over the others. Law enforcement in the United States is made up of about 18,000 federal, state, county, and local agencies. Each agency has varying legal and geographic jurisdictions, ranging from single-officer police departments to those with more than 30,000 officers. The most common type of agency is the small town police department that employs 10 or fewer officers. The decentralized, fragmented, and local nature of law enforcement in the United States makes it challenging to accurately count the number of agencies and officers."