Canadian Auto ID Cards
A U.S. traveler in Canada is required to carry a motor vehicle liability card, plus vehicle ownership papers. A copy of the automobile policy is recommended to be carried. You should also carry a Canadian Non-Resident Inter-provincial Motor Vehicle Liability Card which is strongly recommended.
The Canadian Non-Resident Inter-provincial Motor Vehicle Liability Card is proof of that your US auto policy liability limits meet the minimum requirements for all Canadian provinces and territories and that your coverage extends to Canada and its territories.
U.S. travelers who do not carry a Canadian Non-Resident Inter-provincial Motor Vehicle Liability Card and are stopped by Canadian police or are in an accident while driving in Canada risk being fined or having their vehicle impounded until proof of proper coverage is obtained.