Foreign Traveler Passes A traveler that is from any nation other than the U.S.A. or Mexico will have to have proper paperwork as indicated by each of the countries from which they are traveling. When entering the system, they will like all other passengers have to prove their intent, i.e., visiting a state or national park, business, or traveling through. They also will have to have the proper paperwork for the station for which they will be exiting the system, i.e., U.S.A. or Mexico. "ESTA is an automated system that determines the eligibility of visitors to travel to the U.S. under the Visa Waiver Program (VWP). Authorization via ESTA does not determine whether a traveler is admissible to the United States. U.S. Customs and Border Protection (CBP) officers determine admissibility upon travelers’ arrival. The ESTA application collects biographic information and answers to VWP eligibility questions. ESTA applications may be submitted at any time prior to travel, though it is recommended that travelers apply as soon as they begin preparing travel plans or prior to purchasing airline tickets.  Ref. Wikipedia ESTA is not needed when arriving by land from Canada or Mexico" Ref. Wikipedia Index of ... e-Passports ESTA - Electronic System for Travel Authorization Immigration - From Tucson News Visa Waiver Program