Under section 101(a)(22) of the Immigration and Nationality Act, "the term 'national of the United States' means (A) a citizen of the United States, or (B) a person who, though not a citizen of the United States, owes permanent allegiance to the United States." Those in category (B) include natives of American Samoa.

The Icelandic Nationality Act No 100/1952 specifies the categories of persons to whom Iceland accords citizenship. This includes, but is not limited to, people born to at least one parent holding Icelandic citizenship at the time of birth, people who have become naturalized Icelandic citizens, and people who are able to declare Icelandic citizenship under specific circumstances. Additionally, Iceland's parliament, the Althingi, may confer citizenship on those who petition for Icelandic citizenship. Since July 1, 2003, Iceland permits dual citizenship.