National parks are administered by the Department of the Interior and national forests by the Department of Agriculture. The National Park Service is mandated to preserve resources unimpaired, while the Forest Service is mandated to wisely manage resources for many sustainable uses. Six national forests surround Yellowstone National Park. How many rangers work in Yellowstone? Approximately 738 people work for the National Park Service during the peak summer season. Approximately 386 are permanent, year-round employees. Park rangers work in education, resource management, law enforcement, emergency medical services, and backcountry operations. Other employees specialize in research, maintenance, management, administration, trail maintenance, fire management, and fee collection.