Park ranger
A park ranger, park warden, or forest ranger is a person entrusted with protecting and preserving parklands – national, state, provincial, or local parks. "Parks" may be broadly defined by some systems in this context, and include protected culturally or historically important built environments, and is not limited to the natural environment. Different countries use different names for the position. "Warden" is the favored term in Canada, Ireland, and the United Kingdom. Within the United States, the National Park Service refers to the position as a park ranger. The U.S. Forest Service refers to the position as a forest ranger. Other countries use the term "park warden" or "game warden" to describe this occupation. The profession includes a number of disciplines and specializations, and park rangers are often required to be proficient in more than one.
National Park Service
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. 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 and share law enforcement jurisdiction in all lands administered by the Service with a force of National Park Rangers tasked with the same law enforcement powers and responsibilities.