The Canadian Ministry of Health is going to cap out how many Canadian citizens are allowed to get residency positions in the US.  I don't understand the reason behind it because Canada needs doctors, but it's important to know all the facts if you are Canadian citizen.  For those who plan to get a J-1 visa, you have you re-new your work visa every year but you need Statement of Need one time for ECFMG.

Get US Citizenship If You Can
If you are in basic sciences or in clinical rotations, do your self a favor and find a way to get US green card or citizenship. A strong factor for applicants to get residency is their visa status. Residency programs do have the ability to sponsor you but they will choose not to if they can avoid it because the fees and paperwork is overwhelming; also they don't have the staff to do all that.

If you are a Canadian citizen without US green card or US citizenship then I strongly advise you to NOT apply to any international medical school.  The Canadian government has put a cap on how many Statement of Need (SON) documents that will be issued.

In order for the ECFMG to sponsor your J-1 visa, you need a SON from the Canadian government to be sent to ECFMG.  The SON is needed because after you finish your residency training or fellowship, you are to return to Canada and stay there for 2 years before you are allowed to come back to the US for a job.