All persons traveling by air outside of the United States are required to present a passport book. On June 1, 2009, the U.S. government implemented the full requirements of the land and sea phase of the Western Hemisphere Travel Initiative.
The proposed rules require most U.S. citizens entering the United States at sea or land ports from Mexico, Canada, Bermuda, and the countries of the Caribbean to have a passport book or passport card. Information for specific destinations can be found on the U.S. Department of State’s website.