Passport Information
Travel Documents
After December 31, 2006 passports will be required to enter the U.S. when arriving by air.
After June 1, 2009 passports will be required to enter the U.S. by ground as well as air.
U.S. citizens traveling to Canada should be prepared to show either a U.S. passport, or other proof of U.S. citizenship and government-issued photo ID. A driver's license is not proof of citizenship but can serve as a photo ID in support of other proof such as a birth certificate.
An original green card is proof of permanent U.S. residence and together with a photo ID will also suffice.