Well, the simplest way would seem to be to just duplicate the SQL structure and code then have the application use an appropriate connection string depending on which country the user is from. Whenever you take that approach you need to make sure that it's somewhat locked down to ensure each instance stays in sync as far as code changes in SQL though.

If the data only needs to be in its respective country, not necessarily completely separate, you might use the US DB as the "master" since that's where your site is hosted. Then just replicate the Canadian data to the SQL instance there like what Steve suggested. Or just replicated all of it and have a backup if that's not an issue.