Passport requirement laws have undergone changes in many countries since 9/11, and Canada and the US are among them. If you are planning travel by air to any country, the Airlines may have additional requirements beyond those of the country to which you are traveling. You can check with the Airline to be sure of the requirements before the planned trip, this information is usually available online at the Airline's web pages. But as a general rule, it is best for US travelers to have a valid US passport for all travel nowadays (and in some cases, also a visa).

Travel by air to and from Canada:

Currently (February 2009) all air travelers are required to show a valid passport to enter the US (see WHTI below), even US citizens returning from travel outside the US, and, even when coming from Canada. For that reason, if you are traveling to Canada by air, you will need a passport to be able to return home by air. The Canadian laws allow you to enter Canada by air using a valid passport or other valid equivalent travel document (see below for details). But only a passport will allow your reentry to the US on the return trip by air.

Travel by land and sea between Canada and the US:

Until June 2009, when entering Canada via land or sea, you may also pass the border by showing "proof of US citizenship" (such as original birth certificate or notorized copy) and photo ID. [Permanent alien residents of the US must show "green cards".]

After June 1, 2009, all visitors traveling to Canada by land and sea will be required to show passports or valid equivalent travel documents, "proof of citizenship" alone will no longer meet the entry requirements.

As of the passage of WHTI in 2004, travelers entering or reentering the US by land or sea need to have a passport orvalid equivalent travel document. So, even though Canada will allow you to enter with only "proof of citizenship" (for now), to get back in the US, that "proof of citizenship" alone will not suffice. A passport or valid equivalent documents are currently required to cross back into the US by land or sea.

Bottom line US/Canadian travel: You will be better off for all travel to have a valid passport, it will make border crossings faster and may be the only documentation allowed in some travel situations.

To enter Canada after June 1, 2009 by air, land, or sea, all travelers from all countries will need a passport or valid equivalent travel documents.

To return to the US now (and after June 1, 2009), travelers by air need a passport, no other documentation will be accepted.

Travelers coming back into the US on land and sea need a passport or valid equivalent travel documents as described below.

Additional information:

WHTI: Western Hemisphere Travel Initiative, describes the documentation requirements introduced by the US to increase border safety since 2004.

Canadian "valid equivalent travel documents":

* NEXUS card, a pre-approval card developed via agreement between US and Canada for use in air, land, and sea travel (exceptions described above). * Enhanced Driver's License (EDL), available only in Washington State, New York State, and soon in Vermont for use in land and sea travel only. * US Passport Card, for land and sea travel only, not valid for air travel. * FAST/Expres card, available only to commercial truck drivers.