Different languages use different terms for citizens of the United States. All forms of English refer to US citizens as Americans, a term deriving from the United States of America, the country's official name. In the English context, it came to refer to inhabitants of British America, and then the United States.
These units are a subset of the areas in the United States National Park System, and nearly all participate in the national park passport stamps program. National Park System units are found in all 50 states, in the District of Columbia, and in the U.S. territories of Guam, American Samoa, the U.S. Virgin Islands, and Puerto Rico.