Be careful if you are a Canadian in the US!

There are reciprocal agreements between all US states and Canadian provinces regarding drivers licences and vehicle registrations. All allow for traveling in/through a particular jurisdiction with documentation from another region in those countries. Passports are required to travel by sea or air between our two countries but not by land (this was an exemption after 9-11 and has continually been extended). However at either border, persons from the foreign country can be refused entry for almost any reason - we're each others' guests. We always produce our passports at the border regardless.