Pub. L. 82-414 § 301(a)(7) grants citizenship at birth by law, i.e. naturalization.
7 FAM 1131.6-3 Not Citizens by “Naturalization”
(CT:CON-349; 12-13-2010)
Section 201(g) NA and section 301(g) INA (8 U.S.C. 1401(g)) (formerly section 301(a)(7) INA) both specify that naturalization is “the conferring of nationality of a state upon a person after birth.” Clearly, then, Americans who acquired their citizenship by birth abroad to U.S. citizens are not considered naturalized citizens under either act.