Beginning January 23, 2007, ALL persons, including U.S. citizens, traveling by air between the United States and Canada, Mexico, Central and South America, the Caribbean, and Bermuda will be required to present a valid passport, Air NEXUS card, or U.S. Coast Guard Merchant Mariner Document, or an Alien Registration Card, Form I-551, if applicable.

Read MSN Travel's informative article on new Homeland Security guidelines: Your Passport: Don't Leave Home Without It