There would be no bar to doing so at present, although you should make an advance appointment with the Canadian immigration authorities to avoid being directed back to the USA.Also, you should be aware that provisions limiting the possibility of applying for such status from the USA have been approved and are awaiting implementation. The current expectation is that this will occur in September.
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CAMPBELL, COHEN - attorneys at law
tel:514.937.9445 / fax:514.937.2618
info@canadavisa.com
http://www.canadavisa.com