19 CFR § 123.1 - Report of arrival from Canada or Mexico and permission to proceed.
(a) Individuals. Individuals arriving in the United States, unless excepted by voluntary enrollment in and compliance with PORTPASS - a joint Customs Service/Immigration and Naturalization Service facilitated entry program (See, Immigration and Naturalization Regulations at 8 CFR 235.7), must report their arrival to Customs, and failure to report arrival may result in the individual being liable for certain civil and criminal penalties, as provided under 19 U.S.C. 1459, in addition to other penalties applicable under other provisions of law. The specific reporting requirements are as follows:
(1) Individuals not arriving by conveyance. Persons arriving otherwise than by conveyance may enter the U.S. only at those locations specified by the Commissioner of Customs, or his designee, and shall then immediately report their arrival to Customs. Such persons shall not depart from the Customs port or station until authorized to do so by the appropriate Customs officer.
(2) Persons arriving aboard a conveyance that reported its arrival. Persons aboard a conveyance the arrival of which has been reported to Customs at locations specified by the Commissioner of Customs, or his designee in accordance with section 1433, 1644 or 1644a of title 19, United States Code (19 U.S.C. 1433, 1644, 1644a), shall remain on board until authorized by Customs to depart, and shall then immediately report to the designated Customs facility together with all articles accompanying them.
(3) Persons arriving aboard a conveyance that has not reported its arrival. Persons aboard a conveyance the arrival of which has not been reported in accordance with the laws referred to in paragraph (a)(2) of this section, shall immediately notify a Customs officer and report their arrival, together with appropriate information concerning the conveyance on or in which they arrived, at a location or locations specified by the Commissioner of Customs, or his designee and shall present themselves and their property for Customs inspection and examination.
(b) Vehicles. Vehicles may arrive in the U.S. only at a designated port of entry (see § 101.3 of this chapter) or Customs station if the Commissioner of Customs, or his designee authorizes entry at that station (see § 101.4 of this chapter). Upon arrival of the vehicle in the U.S., the driver, unless he or she and all of the vehicle's occupants are excepted by enrollment in, and in compliance with, PORTPASS - a joint Customs Service/Immigration and Naturalization Service facilitated entry program (See, Immigration and Naturalization Regulations at 8 CFR 235.1 and 286.8), immediately shall report such arrival to Customs, and shall not depart or discharge any passenger or merchandise (including baggage) without authorization by the appropriate Customs officer.
(c) Vessels. For report of arrival requirements applicable to all vessels, regardless of tonnage, and arriving from any location, see § 4.2 of this chapter.
(d) Method of reporting. Report of arrival under paragraphs (a), (b), and (c) of this section shall be made in person unless the port director, by local instructions, requires that it be made by some other specific means. Such local instructions issued by the port director will be made available to interested parties by posting in Customs offices, publication in a newspaper of general circulation in the Customs port that supervises the location, and/or other appropriate means.