73 FR 32440 (June 9, 2008)
This DHS interim final rule established the Electronic System for Travel Authorization (ESTA), which is became mandatory for Visa Waiver Program (VWP) travelers on January 12, 2009. ESTA is an automated, electronic system for screening passengers before they begin travel to the United States under the VWP. DHS began accepting voluntary ESTA applications starting on August 1, 2008.
A prospective VWP traveler must obtain an electronic authorization through ESTA prior to boarding a U.S.-bound airplane or cruise ship.