American citizens or foreigners must have a valid passport to enter Canada. Depending on your country of origin, you may also need a visa. We suggest checking with the competent authorities of your government, embassy or Canadian consulate to know what documents you need to enter Canada, depending on your situation.
Air carriers must ensure that your travel permits are valid and suitable to enter Canada. If you do not have the necessary documents, you may be denied boarding. Contact your travel agent for more information.
Some useful links:
http://travel.state.gov/travel/cis_pa_tw/cis/cis_1082.html – U.S. Department of State
http://www.cbsa-asfc.gc.ca/menu-fra.html – Canada Border Services Agency
http://www.goingtocanada.gc.ca/CIC/display-afficher.do?id=&lang=eng – Going to Canada – Government of Canada