(1) The term “State”, except where otherwise provided, includes the District of Columbia and the Commonwealth of Puerto Rico, and when used in subchapters IV, V, VII, XI, XIX, and XXI includes the Virgin Islands and Guam. Such term when used in subchapters III, IX, and XII also includes the Virgin Islands. Such term when used in subchapter V and in part B of this subchapter also includes American Samoa, the Northern Mariana Islands, and the Trust Territory of the Pacific Islands. Such term when used in subchapters XIX and XXI also includes the Northern Mariana Islands and American Samoa. In the case of Puerto Rico, the Virgin Islands, and Guam, subchapters I, X, and XIV, and subchapter XVI (as in effect without regard to the amendment made by section 301 of the Social Security Amendments of 1972) shall continue to apply, and the term “State” when used in such subchapters (but not in subchapter XVI as in effect pursuant to such amendment after December 31, 1973 ) includes Puerto Rico, the Virgin Islands, and Guam. Such term when used in subchapter XX also includes the Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands. Such term when used in subchapter IV also includes American Samoa.