19 U.S. Code § 2611 - Certain material and articles exempt from this chapter
The provisions of this chapter shall not apply to—
(1) any archaeological or ethnological material or any article of cultural property which is imported into the United States for temporary exhibition or display if such material or article is immune from seizure under judicial process pursuant to section 2459 of title 22; or
(2) any designated archaeological or ethnological material or any article of cultural property imported into the United States if such material or article—
(A) has been held in the United States for a period of not less than three consecutive years by a recognized museum or religious or secular monument or similar institution, and was purchased by that institution for value, in good faith, and without notice that such material or article was imported in violation of this chapter, but only if—
(i) the acquisition of such material or article has been reported in a publication of such institution, any regularly published newspaper or periodical with a circulation of at least fifty thousand, or a periodical or exhibition catalog which is concerned with the type of article or materials sought to be exempted from this chapter,
(ii) such material or article has been exhibited to the public for a period or periods aggregating at least one year during such three-year period, or
(B) if subparagraph (A) does not apply, has been within the United States for a period of not less than ten consecutive years and has been exhibited for not less than five years during such period in a recognized museum or religious or secular monument or similar institution in the Unites  States open to the public; or
(C) if subparagraphs (A) and (B) do not apply, has been within the United States for a period of not less than ten consecutive years and the State Party concerned has received or should have received during such period fair notice (through such adequate and accessible publication, or other means, as the Secretary shall by regulation prescribe) of its location within the United States; and
(D) if none of the preceding subparagraphs apply, has been within the United States for a period of not less than twenty consecutive years and the claimant establishes that it purchased the material or article for value without knowledge or reason to believe that it was imported in violation of law.
 So in original. Probably should be “United”.