Ok.. there is a little bit of confusion on this ... So I did some research today... and here are the results.
There are a number of large debit system clearinghouses in the United States. Two of the biggest are NYCE (New York Cash Exchange) and Maestro (a division of Mastercard). Generally speaking, most large retailers accept both of these. Some of your mom & pop shops might accept one but not the other. My own personal experience is that I have yet to find a merchant who didn't accept BOTH on my drives from Houlton, ME to Orlando, FL. That said, you might just be lucky enough to find that one merchant that I could not.
RBC, TD, ScotiaBank uses the NYCE system for debit in the United States. If you are a customer of one those institutions, you're looking for the NYCE logo. If the merchant's system refuses your transaction, they're probably not part of the NYCE network. I'm with TD myself and have used this feature on NYCE merchants from Walmart and Walgreens, to Target, Chili's and even McDonalds.
BMO customers use the Maestro debit network. So you're looking for the Maestro logo to know if you can use your debit card at that merchant. The Maestro logo looks like the Mastercard logo, except it says Maestro. Rule of thumb: If they have a debit machine AT ALL and accept Mastercard, generally that means it accepts Maestro as well.
CIBC does not have a webpage that explains whether or not U.S. debit options are available to their clientele. So for now -- that one is a question mark. President's Choice Financial is just CIBC rebranded.. so the same rules apply to PC Banking customers - call to find out but there doesn't appear to be a U.S. debit option available to you.
Most Canadian credit unions/Caisse Populaire branches actually offer the 'Mastercard' debit card option where your card has an MC logo and is accepted like a credit card without a PIN whereever MC is accepted.
ScotiaBank Info:
http://www.scotiabank.com/cda/content/0,1608,CID8186_LIDen,00.html
Royal Bank (RBC) Info:
http://www.rbcroyalbank.com/RBC:RyVkTo71JscAIKAQ2g0/products/deposits/debit-card.html[
Bank of Montreal BMO Info:
http://www4.bmo.com/bmo/popup_template/0,4442,35649_67222,00.html?pChannelId=0#acc_access
TD Bank Info:
https://www.tdcanadatrust.com/ebanking/crossborder.jsp?referer=http://www.tdcanadatrust.com/
If you bank at a location other than one of these listed, you should call your financial institution to find out what options are available to you for DEBIT purchases in the U.S.
ALL of the above providers allow ATM access in the states... usually for a fee.
Hope this clears it up.
Knox