Upvote:1
Canada does not even require US citizens to have a passport to enter Canada, so there's no way they'd care about the expiration date of the passport you do have.
From the site linked above (emphasis added):
Non-Canadians entering Canada
When you enter Canada, a Canada Border Services Agency officer may ask to see your passport and a valid visa, if you need one. If you are a citizen of the United States, you do not need a passport to enter Canada, but you should carry proof of your citizenship, such as a birth certificate, certificate of citizenship or naturalization, as well as photo identification