Passport requirements for US citizens crossing

Western Hemisphere Travel Initiative

AIR TRAVEL

ALL PERSONS traveling by air outside of the United States are required to present a passport or other valid travel document to enter or re-enter the United States.
LAND AND SEA TRAVEL
The following summarizes information available on the Department of Homeland Security’s website.

• CURRENTLY: 
  U.S. citizens need to present either (a) a passport, passport card (available in spring 2008), or WHTI-compliant document; or (b) a government-issued photo ID, such as a driver’s license, along with proof of citizenship, such as a birth certificate.
• LATER:
  As early as June 1, 2009, the U.S. government will implement the full requirements of the land and sea phase of WHTI.  The proposed rules require most U.S. citizens entering the United States at sea or land ports of entry to have a passport, passport card, or WHTI-compliant document. 

Note: The passport requirement does NOT apply to U.S. citizens traveling to or returning directly from a U.S. territory.

U.S. PASSPORT AND WHTI COMPLIANT DOCUMENTS: 

• U.S. Passport: U.S. citizens may present a valid U.S. passport when traveling via air, land or sea between the U.S. and the aforementioned Western Hemisphere countries.
• The Passport Card: U.S. citizens may begin applying in advance for this new, limited-use, wallet-size passport card beginning February 1, 2008. We expect cards will be available and mailed to applicants in spring 2008. When available it will only be valid for land and sea travel between the U.S. and Canada, Mexico, the Caribbean region, and Bermuda.
• WHTI-Compliant Travel Documents for U.S. citizen travel via land or sea, as of January 31, 2008:
• • Trusted Traveler Cards (NEXUS, SENTRI, or FAST)
  • State Issued Enhanced Driver’s License (when available)
  • Enhanced Tribal Cards (when available)
  • U.S. Military Identification with Military Travel Orders
  • U.S. Merchant Mariner Document when traveling in conjunction with official maritime business
  • Native American Tribal Photo Identification Card
  • Form I-872 American Indian Card

For further information see U.S. Customs and Border protection. 
ABOUT WHTI
The Western Hemisphere Travel Initiative is a result of the Intelligence Reform and Prevention Act of 2004 (IRTPA), requiring all travelers to present a passport or other document that denotes identity and citizenship when entering the U.S.
The goal of the initiative is to strengthen U.S. border security while facilitating entry for U.S. citizens and legitimate foreign visitors by providing standardized documentation that enables the Department of Homeland Security to quickly and reliably identify a traveler.
Federal Regulations

• Final Rule - Air Phase ( PDF)
• Final Rule - Passport Card ( PDF)
• Notice of Proposed Rulemaking on Land/Sea Rule ( PDF)

Other Relevant Links

• Department of Homeland Security
• U.S. Customs and Border Protection
• Applying for a Passport