49 U.S.C. § 44102: Registration requirements

(a) Eligibility.—An aircraft may be registered under section 44103 of this title only when the aircraft is—(1) not registered under the laws of a foreign country and is owned by—(A) a citizen of the United States; (B) an individual citizen of a foreign country lawfully admitted for permanent residence in the United States; or (C) a corporation not a citizen of the United States when the corporation is organized and doing business under the laws of the United States or a State, and the aircraft is based and primarily used in the United States; or (2) an aircraft of—(A) the United States Government; or (B) a State, the District of Columbia, a territory or possession of the United States, or a political subdivision of a State, territory, or possession. (b) Duty To Define Certain Term.—In carrying out subsection (a)(1)(C) of this section, the Secretary of Transportation shall define “based and primarily used in the United States”.