26 CFR § 31.3306(j)-1 - State, United States, and citizen.
(a) When used in the regulations in this subpart, the term “State” includes the District of Columbia, the Territories of Alaska and Hawaii before their admission as States, and (when used with respect to remuneration paid after 1960 for services performed after 1960) the Commonwealth of Puerto Rico.
(b) When used in the regulations in this subpart, the term “United States”, when used in a geographical sense, means the several States (including the Territories of Alaska and Hawaii before their admission as States), and the District of Columbia. When used in the regulations in this subpart with respect to remuneration paid after 1960 for services performed after 1960, the term “United States” also includes the Commonwealth of Puerto Rico when the term is used in a geographical sense, and the term “citizen of the United States” includes a citizen of the Commonwealth of Puerto Rico.