Canada doesn't require a passport for entry from United States citizens. If that U.S. citizen is entering Canada from a third-country, such as England, he will be required to present a passport book. Travel to countries within the Western Hemisphere -- Bermuda, Mexico and the Caribbean -- will also not require a passport book. The U.S. territories which include Guam, American Samoa, Wake Island, Midway Islands, Puerto Rico, United States Virgin Islands and Northern Mariana Islands don't require U.S. citizens to present a current passport book.
NEXUS cards are special travel cards used to expedite crossing the U.S. and Canadian border. Western Hemisphere Travel Initiative, or WHTI, compliant documents can also be used to travel to countries in the Western Hemisphere including Canada, Mexico, Bermuda and the Caribbean. These complaint documents include the passport card or valid photo ID. Not all types of compliant documents are accepted for entry into every country that accepts WHTI documents. Only U.S. territories will accept a valid state or military identification card for entry. Birth certificates are acceptable to enter Canada, if the traveler is under 16. Mexico requires a passport card or book to travel within the interior of Mexico, or beyond the "border zone."
Some countries require additional documents for entry. Afghanistan, for example, also requires a valid visa and U.S. passport book to enter into the country. Albania requires that those wishing to enter the country have a passport book that has been valid for at least six months before being allowed to enter the country. You don't need a visa to enter Albania, but if you travel without one, you may be charged a entry stamp fee. To check for additional country specific requirements, look at the U.S. Department of State website.
To re-enter the United States by land, air or sea from Canada, you must present a valid U.S. passport, passport card, NEXUS card, an enhanced driver's license or another Western Hemisphere Travel Initiative (WHTI) compliant document. Those U.S. citizens under 16, or under 19 if traveling with a school, youth or religious group, may re-enter the U.S. with just a birth certificate. To re-enter the U.S. by air from the Bahamas, you must have a valid U.S. passport, although only valid ID is required to enter. To re-enter by sea, you must have a passport, passport card or WHTI compliant document. To re-enter the U.S. from Mexico, you must have a U.S. passport book or card. To re-enter the U.S. from Puerto Rico or other U.S. territories in the Caribbean, you will need valid state or military ID and proof of U.S. citizenship such as a birth certificate.
