On June 1, 2009, the U.S. government will implement the final requirements of the land and sea phase of the Western Hemisphere Travel Initiative. The rules require U.S. citizens re-entering the United States at sea or land ports of entry to have a passport, passport card, or other travel document approved by the Department of Homeland Security.
Those citizens under the age of 16 will be able to present the original or a copy of their birth certificate, or other proof of U.S. citizenship, such as a naturalization certificate or citizenship card.
U.S. citizens can apply for a U.S. Passport Card, which facilitates entry and expedites document processing at U.S. land and sea ports of entry when arriving from Canada, Mexico, the Caribbean (excluding P.R. and U.S. Virgin Islands), and Bermuda. The card may not be used for air travel.