How many states have national parks?

As of 2015, there are 59 fully fledged national parks in the United States that are distributed among 27 states and two territories (American Samoa and the U.S. Virgin Islands).

Not all of the sites in the National Park System are classified as "national parks." Other categories under the umbrella of the National Park Service include national monuments, preserves, recreation areas, seashores, rivers, reserves, historic and scenic trails, parkways, and cemeteries. There are also areas included for their historical importance, including historic parks, historic site, battlefield parks, military parks, battlefields, and memorials.