As of December 2009:

• U. S. citizens entering Canada are required to have a "valid travel document, such as a passport" for entry into Canada. For more information on eligibility or to get requirements for travel from other countries visit www.cic.gc.ca
• U. S. citizens returning to the United States from Canada are required to "present one of the following travel documents: U.S. Passport or Passport Card, Enhanced Driver's License (EDL) or Trusted Traveler Card (NEXUS, SENTRI or FAST)". For more information visit www.cbp.gov