Canada's Immigration and Refugee Protection Act ( http://laws-lois.justice.gc.ca/eng/a...2.5/index.html ) does not require a passport for entry at a land border crossing. There may have been extenuating circumstances in your case that precluded entry. If there is a reasonable expectation that the United States will refuse admission on re-entry, admission to Canada may be denied as the person would be stuck with no means of support.
Originally Posted by EvryDayRide
Citizens of Canada and the US may not be denied entry to the country of citizenship. Without a passport, verification of citizenship may be an involved process. With a passport there are no grounds to deny entry to the country of citizenship. A dual citizen of both the US and Canada cannot be denied entry to either, provided it can be proved through information databases.
Originally Posted by Montauk