Exporting to the United States – A Team Canada Inc Publication

6.6 If you're not a Canadian citizen

The regulations governing entry into the U.S. of non-Canadians vary according to citizenship and may change without much notice. Consequently, if you're a Canadian permanent resident (defined as "someone who has been allowed to enter Canada as an immigrant, but who has not become a Canadian citizen"), check your status with U.S. immigration officials before you set out on your business trip. You can get information about doing this from the United States Citizenship and Immigration Services. You might also wish to query the Government of Canada's Consular Affairs Bureau for additional information about your particular situation.

Having left Canada, you'll presumably want to return. If you're a Canadian permanent resident, you'll need a Canadian Permanent Resident Card to do so. This card has been required for re-entry since December 31, 2003, and replaces the IMM 1000 Record of Landing document you may have used in the past. You can apply for the card through Citizenship and Immigration Canada's Web site or by calling 1 800 255-4541.