Obama historisk: Öppnade 22 nationalparker i USA

The National Park System of the United States is the collection of physical properties owned or administered by the National Park Service. This includes all areas designated national parks and most national monuments, as well as several other types of protected areas of the United States. As of August 2016, there are 413 units of the National Park System. However, this number is somewhat misleading. For example, Denali National Park and Preserve is counted as two units, since the same name applies to a national park and an adjacent national preserve. Yet Jean Lafitte National Historical Park and Preserve is counted as one unit, despite its double designation. Counting methodology is rooted in the language of a park's enabling legislation. Elsewhere, Fort Moultrie is not counted as a unit because it is considered a feature of Fort Sumter National Monument. In addition to areas of the National Park System, the National Park Service also provides technical and financial assistance to several affiliated areas authorized by Congress. Affiliated areas are marked on the lists below. The National Register of Historic Places is administered by the Park Service (with nearly 79,000 entries) and automatically includes all National Park System areas designated because of their historic significance. This includes all National Historical Parks/Historic Sites, National Battlefields/Military Parks, National Memorials, and some National Monuments. Units are found in all 50 states, in Washington, D.C., and in the U.S. territories of Guam, the Northern Mariana Islands, American Samoa, the U.S. Virgin Islands, and Puerto Rico. Nearly all units managed by the National Park Service participate in the National Park Passport Stamps program.