8 CFR § 217.3 - Maintenance of status.
(a) Satisfactory departure. If an emergency prevents an alien admitted under this part from departing from the United States within his or her period of authorized stay, the district director having jurisdiction over the place of the alien's temporary stay may, in his or her discretion, grant a period of satisfactory departure not to exceed 30 days. If departure is accomplished during that period, the alien is to be regarded as having satisfactorily accomplished the visit without overstaying the allotted time.
(b) Readmission after departure to contiguous territory or adjacent island. An alien admitted to the United States under this part may be readmitted to the United States after a departure to foreign contiguous territory or adjacent island for the balance of his or her original Visa Waiver Pilot Program admission period if he or she is otherwise admissible and meets all the conditions of this part with the exception of arrival on a signatory carrier.