Traveling to Canada and back...do I need a passport traveling by car?

Hello,
I am here since 1968, and still have a green card. Will I need a passport to get back home to the US, if I travel by car, or will my Green-card be enough?

Thanks.

how come your green card has not yet expired?

You will need your passport and green card to get into Canada.

you will need both.

Based on the gov't side below, your Alien Registration card, which is your green card should be enough.

From the Gov't site:
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.

As early as January 1, 2008, ALL persons, including U.S. citizens, traveling between the U.S. and Canada, Mexico, Central and South America, the Caribbean, and Bermuda by land or sea (including ferries), may be required to present a valid passport or other documents as determined by the Department of Homeland Security. While recent legislative changes permit a later deadline, the Departments of State and Homeland Security are working to meet all requirements as soon as possible. Ample advance notice will be provided to enable the public to obtain passports or passport cards for land/sea entries.

Source(s):
http://travel.state.gov/travel/cbpmc/cbp...