Some info here:
Use CDN debit cards in USAWe used to use our CDN debit cards only to get cash at US ATMs (some had ATM fee and some not) but now we exclusively use our debit and credit cards issued by USA banks for everything.
At one time CDN debit cards were not generally accepted in the US for retail purchases but that has now changed with the NYCE system as noted in the link above and I think some CDN banks (CIBC and TD included I think) now issue debit cards with the Visa or Mastercard symbol which can access your CDN accounts for retail purchases via the US debit processing system.