As of 2020, more than 800,000 sworn law enforcement officers have been serving in the United States. About 137,000 of those officers work for federal law enforcement agencies.Law enforcement operates primarily through governmental police agencies. There are 17,985 police agencies in the United States which include local police departments, county sheriff's offices, state troopers, and federal law enforcement agencies. The law enforcement purposes of these agencies are the investigation of suspected criminal activity, referral of the results of investigations to state or federal prosecutors, and the temporary detention of suspected criminals pending judicial action. Law enforcement agencies, are also commonly charged with the responsibilities of deterring criminal activity and preventing the successful commission of crimes in progress. Other duties may include the service and enforcement of warrants, writs, and other orders of the courts. Law enforcement agencies are also involved in providing first response to emergencies and other threats to public safety; the protection of certain public facilities and infrastructure, such as private property; the maintenance of public order; the protection of public officials; and the operation of some detention facilities (usually at the local level). Source: Wikipedia (en)