U.S. citizens, as defined in § 41.0 of this chapter, are not required to bear U.S. passports when traveling directly between parts of the United States as defined in § 51.1 of this chapter.

A U.S. citizen is not required to bear a valid U.S. passport to enter or depart the United States:

When traveling as a member of the Armed Forces of the United States on active duty and when he or she is in the uniform of, or bears documents identifying him or her as a member of, such Armed Forces, when under official orders or permit of such Armed Forces, and when carrying a military identification card; or

When traveling entirely within the Western Hemisphere on a cruise ship, and when the U.S. citizen boards the cruise ship at a port or place within the United States and returns on the return voyage of the same cruise ship to the same United States port or place from where he or she originally departed. That U.S. citizen may present a government-issued photo identification document in combination with either an original or a copy of his or her birth certificate, a Consular Report of Birth Abroad issued by the Department, or a Certificate of Naturalization issued by U.S. Citizenship and Immigration Services before entering the United States; if the U.S. citizen is under the age of 16, he or she may present either an original or a copy of his or her birth certificate, a Consular Report of Birth Abroad issued by the Department, or a Certificate of Naturalization issued by U.S. Citizenship and Immigration Services; or

When traveling as a U.S. citizen seaman, carrying an unexpired Merchant Marine Document (MMD) in conjunction with maritime business. The MMD is not sufficient to establish citizenship for purposes of issuance of a United States passport under part 51 of this chapter; or

Trusted traveler programs—(i) NEXUS Program. When traveling as a participant in the NEXUS program, he or she may present a valid NEXUS program card when using a NEXUS Air kiosk or when entering the United States from contiguous territory or adjacent islands at a land or sea port-of-entry. A U.S. citizen who enters the United States by pleasure vessel from Canada under the remote inspection system may also present a NEXUS program card;

FAST program. A U.S. citizen who is traveling as a participant in the FAST program may present a valid FAST card when entering the United States from contiguous territory or adjacent islands at a land or sea port-of-entry;

SENTRI program. A U.S. citizen who is traveling as a participant in the SENTRI program may present a valid SENTRI card when entering the United States from contiguous territory or adjacent islands at a land or sea port-of-entry; The NEXUS, FAST, and SENTRI cards are not sufficient to establish citizenship for purposes of issuance of a U.S. passport under part 51 of this chapter; or

When arriving at land ports of entry and sea ports of entry from contiguous territory or adjacent islands, Native American holders of American Indian Cards (Form I-872) issued by U.S. Citizenship and Immigration Services (USCIS) may present those cards; or

When arriving at land or sea ports of entry from contiguous territory or adjacent islands, U.S. citizen holders of a tribal document issued by a United States qualifying tribal entity or group of United States qualifying tribal entities as provided in 8 CFR 235.1(e) may present that document. Tribal documents are not sufficient to establish citizenship for purposes of issuance of a United States passport under part 51 of this chapter; or

When bearing documents or combinations of documents the Secretary of Homeland Security has determined under Section 7209(b) of Public Law 108-458 (8 U.S.C. 1185 note) are sufficient to denote identity and citizenship. Such documents are not sufficient to establish citizenship for purposes of issuance of a U.S. passport under part 51 of this chapter; or

When the U.S. citizen is employed directly or indirectly on the construction, operation, or maintenance of works undertaken in accordance with the treaty concluded on February 3, 1944, between the United States and Mexico regarding the functions of the International Boundary and Water Commission (IBWC), TS 994, 9 Bevans 1166, 59 Stat. 1219, or other related agreements, provided that the U.S. citizen bears an official identification card issued by the IBWC and is traveling in connection with such employment; or

When the Department of State waives, pursuant to EO 13323 of December 30, 2003, Section 2, the requirement with respect to the U.S. citizen because there is an unforeseen emergency; or

When the Department of State waives, pursuant to EO 13323 of December 30, 2003, Sec 2, the requirement with respect to the U.S. citizen for humanitarian or national interest reasons; or

When the U.S. citizen is a child under the age of 19 arriving from contiguous territory in the following circumstances:

Children under age 16. A United States citizen who is under the age of 16 is permitted to present either an original or a copy of his or her birth certificate, a Consular Report of Birth Abroad, or a Certificate of Naturalization issued by U.S. Citizenship and Immigration Services when entering the United States from contiguous territory at land or sea ports-of-entry; or

Groups of children under age 19. A U.S. citizen who is under age 19 and who is traveling with a public or private school group, religious group, social or cultural organization, or team associated with a youth sport organization may present either an original or a copy of his or her birth certificate, a Consular Report of Birth Abroad, or a Certificate of Naturalization issued by U.S. Citizenship and Immigration Services when arriving in the United States from contiguous territory at all land or sea ports of entry, when the group, organization or team is under the supervision of an adult affiliated with the organization and when the child has parental or legal guardian consent to travel. For purposes of this paragraph, an adult is considered to be a person who is age 19 or older. The following requirements will apply:

The group, organization, or team must provide to CBP upon crossing the border on organizational letterhead:

The name of the group, organization or team, and the name of the supervising adult;

A list of the children on the trip; and

For each child, the primary address, primary phone number, date of birth, place of birth, and the name of at least one parent or legal guardian.

The adult leading the group, organization, or team must demonstrate parental or legal guardian consent by certifying in the writing submitted in paragraph (b)(11)(ii)(A) of this section that he or she has obtained for each child the consent of at least one parent or legal guardian.

The procedure described in this paragraph is limited to members of the group, organization, or team who are under age 19. Other members of the group, organization, or team must comply with other applicable document and/or inspection requirements found in 8 CFR parts 211, 212, or 235.