33 CFR 141.25 - Evidence of citizenship.
(1) A valid merchant mariner's document issued by the Coast Guard which shows the holder to be citizen of the United States.
(2) An original or certified copy of a birth certificate or birth registration issued by a state or the District of Columbia.
(3) A United States passport.
(4) A Certificate of Citizenship issued by the Immigration and Naturalization Service.
(5) A Certificate of Naturalization issued by a Naturalization Court.
(6) A letter from the Coast Guard issued under paragraph (d) of this section.
(b) If a person does not have one of the documents listed in paragraphs (a)(1) through (a)(6) of this section, that person may appear in person before an Officer in Charge, Marine Inspection, and submit one or more of the following documents which may be considered as evidence that the applicant is a citizen of the United States:
(1) A Certificate of Derivative Citizenship or a Certificate of Naturalization of either parent and a birth certificate of the applicant or other evidence satisfactorily establishing that the applicant was under 21 years of age at the time of the parent's naturalization.
(2) An original or certified copy of a birth certificate from a political jurisdiction outside the United States which demonstrates citizenship status.
(3) A Baptismal certificate or parish record recorded within one year after birth.
(4) A statement of a practicing physician certifying that the physician attended the birth and has a record showing the date on which the birth occurred.
(5) A commission, or evidence of commission, in the Armed Forces of the United States which shows the holder to be a citizen of the United States.
(6) A continuous discharge book or certificate of identification issued by the Coast Guard or the former Bureau of Marine Inspection, provided the document shows that the applicant produced satisfactory evidence of citizenship at the time the document was issued.
(7) A delayed certificate of birth issued under a state seal, provided there are no collateral facts indicating fraud in its procurement.
(8) A report of the Census Bureau showing the earliest available record of the applicant's age or birth.
(9) Affidavits of parents, relatives, or two or more responsible citizens of the United States, school records; immigration records; insurance policies; or other records which support the citizenship claim.
(c) In any case where doubt exists concerning evidence of citizenship submitted under paragraph (b) of this section, the Officer in Charge, Marine Inspection, may refer the matter to the United States Immigration and Naturalization Service for an advisory opinion.
(d) If the documents submitted under paragraph (b) of this section are determined by the Officer in Charge, Marine Inspection, to be sufficient evidence that the applicant is a citizen of the United States, the Coast Guard issues the applicant a letter acknowledging this determination.