Canadian Travel Confusion Continues
Just to clarify: during 2007, you will a passport to enter the U.S. from Canada if you are traveling by air.
That means airlines will NOT let U.S. residents fly into Canada unless they have a passport (with a few exceptions that do not apply to the majority of travellers) for the return trip.
During 2007, auto, bus, and rail passengers, if U.S. citizens, can continue to enter the U.S. from Canada with either a passport OR an official copy of their birth certificate ALONG WITH a government-issued photo id such as a driver's license. (A driver's license alone does not prove citizenship.)
Although passengers entering the U.S. from Canada by ship do not yet officially need a passport, they should contact their cruise company for its policy, which may be more stringent than the government one.