Hello,
I just found this website with information for Holders of Canadian and American Citizenship.
It has the information about using your Canadian Passport to enter Canada and the American Passport for entering the USA.
http://www.amcits.com/enter_canada.asp
I am sure that if you travel by car and it is licensed in the USA, then you better have your U.S. information handy so they do not think that you are trying to import the vehicle into Canada.....
I just found this website with information for Holders of Canadian and American Citizenship.
It has the information about using your Canadian Passport to enter Canada and the American Passport for entering the USA.
http://www.amcits.com/enter_canada.asp
I am sure that if you travel by car and it is licensed in the USA, then you better have your U.S. information handy so they do not think that you are trying to import the vehicle into Canada.....