The protected areas of the United States are managed by an array of different federal, state, tribal and local level authorities and receive widely varying levels of protection. Some areas are managed as wilderness, while others are operated with acceptable commercial exploitation. As of 2015[update], the 25,800 protected areas covered 1,294,476 km2 (499,800 sq mi), or 14 percent of the land area of the United States. This is also one-tenth of the protected land area of the world. The U.S. also had a total of 787 National Marine Protected Areas, covering an additional 1,271,408 km2 (490,893 sq mi), or 12 percent of the total marine area of the United States.
Some areas are managed in concert between levels of government. The Father Marquette National Memorial is an example of a federal park operated by a state park system, while Kal-Haven Trail is an example of a state park operated by county-level government.
As of 2007[update], according to the United Nations Environment Programme, the U.S. had a total of 6,770 terrestrial nationally designated (federal) protected areas. Federal level protected areas are managed by a variety of agencies, most of which are a part of the National Park Service, a bureau of the United States Department of the Interior. They are often considered the crown jewels of the protected areas. Other areas are managed by the United States Forest Service, the Bureau of Land Management and the United States Fish and Wildlife Service. The United States Army Corps of Engineers is claimed to provide 30 percent of the recreational opportunities on federal lands, mainly through lakes and waterways that they manage.