It's mostly a disambiguation thing, although it's definitely more popular in some circles than others. A similar term sometimes seen in more formal contexts is

It's mostly a disambiguation thing, although it's definitely more popular in some circles than others. A similar term sometimes seen in more formal contexts is "US-American". "American" is sometimes construed to include all of North, Central, and South America, predominantly in Spanish and Portuguese languages (e.g. the Organization of American States / Organización de los Estados Americanos / Organización de los Estados Americanos), as opposed to modern English where the usual collective term is "the Americas".