In general, a driver from any U.S. state is not allowed to enter Canada with a DUI conviction, according to U.S. Customs and Border Protection. However, it is possible to apply for a waiver. Information on how to do so is available through the Canada Border Services Agency.
When Americans with DUIs arrive at ports of entry, Canadian immigration officers decide if they may cross the border, the Government of Canada states. People convicted of any crimes, including DUIs, must demonstrated that a significant amount of time has passed since their offenses. In addition, their potential commission of new crimes must be unlikely.
When traveling from Canada to the United States, a single DUI conviction does not bar entry, U.S. Customs and Border Protection explains. Multiple convictions or a DUI in conjunction with other misdemeanors require waivers.