As of January 23, 2007, citizens of the United States, Canada, Mexico, and Bermuda are required to present a passport to enter the United States when arriving by air from any part of the Western Hemisphere.
The department expects a smooth transition to the new passport requirement based on the numbers of travelers arriving at U.S. airports with passports. Over 90 percent of U.S. citizens, 97 percent of Canadians, and virtually 100 percent of Mexicans and Bermudans flying to the United States immediately before the rule took arrived with passports.
The air requirement is part of the departments of State and Homeland Security’s Western Hemisphere Travel Initiative. This change in travel document requirements is the result of recommendations made by the 9/11 Commission, which Congress subsequently passed into law in the Intelligence Reform and Terrorism Prevention Act of 2004.
A separate proposed rule addressing land and sea travel will be published at a later date with specific requirements for travelers entering the United States through land and sea border crossings. As early as Jan.1, 2008, citizens traveling between the United States and Canada, Mexico, Central and South America, the Caribbean, and Bermuda by land or sea may be required to present a valid passport or other documents as determined by the Department of Homeland Security to enter the United States.