I remember a contestant from Buffalo, NY on Definition once. Buffalo and Toronto are less than a two-hour drive between each other so I guess that's not a total surprise.
I think shows like Jackpot and Bumper Stumpers probably shouldn't count on either list, because they were taped in Canada for simultaneous airing in Canada and the US, and with the involvement of a US production company, so it stands to reason there'd be both Canadian and American contestants.