By plane
There are two international airports in Québec: Montréal-Trudeau Airport and Québec City's Jean-Lesage Airport. Passengers arriving at Montréal-Trudeau Airport can easily travel by shuttle to downtown Montréal, Kingston and Ottawa (3 to 5 departures per day), and Mont-Tremblant (from mid-December to mid-April).
If you are travelling by air, as of January 23, 2007, U.S. Customs will require that you produce a valid passport on your return to the United States, as prescribed by the Western Hemisphere Travel Initiative (WHTI). For people travelling by land or sea, this requirement will come into effect by June 1, 2009. As in the past, to enter Canada, American citizens must be able to produce one of the following items as proof of citizenship: passport, Green Card, a birth certificate, or certificate of citizenship or naturalization, as well as a piece of photo ID.