49 U.S.C. § 44102

1. (a)An aircraft may be registered under section 44103 of this title only when the aircraft is—
   1. (1)not registered under the laws of a foreign country and is owned by—
      1. (A)a citizen of the United States;
      2. (B)an individual citizen of a foreign country lawfully admitted for permanent residence in the United States; or
      3. (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. (2)an aircraft of—
      1. (A)the United States Government; or
      2. (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.
2. (b)In carrying out subsection (a)(1)(C) of this section, the Secretary of Transportation shall define “based and primarily used in the United States”.