The United States Park Police (USPP) is the oldest uniformed federal law enforcement agency in the United States. It functions as a full-service law enforcement agency with responsibilities and jurisdiction in those National Park Service areas primarily located in the Washington, D.C., San Francisco, and New York City areas and certain other government lands. United States Park Police officers have jurisdictional authority in the surrounding metropolitan areas of the three cities it primarily operates in, meaning they possess both state and federal authority. In addition to performing the normal crime prevention, investigation, and apprehension functions of an urban police force, the Park Police are responsible for policing many of the famous monuments in the United States.

The federal government of the United States empowers a wide range of federal law enforcement agencies to maintain law and public order related to matters affecting the country as a whole.