Hey guys, I am a Brazilian citizen, no green card and applied this year and got into Columbia and Tulane. The process is difficult but not impossible, and with good letters and good stats, very feasible. Lotrfan, not to question your sources, but 190 sounds WAAAYYYY off for non green card holders, that is a whole class and given that the best shot we have are at private institutions, and that there seems to be between 3-4 a class in those schools, the total should not be greater than 100, if that.
Autumnleaves, do not take this as a "HUGE bump in the road" to your medical career. If you are truly motivated and committed to this profession, you will get in, either in the US or in Canada, and things will work out for you.
Regarding the actual process, I think the only difference between me and my American counterparts was the number of schools I ended up applying to and the number of interviews that I got. I applied to 17 schools (I initially had 30 but tried to narrow it down to schools that I would attend if admitted) and only got 3 interviews. If I were an American citizen I would add at least 7 interviews to my 3, totalling 10. The truth is that I applied to a lot of schools that didn't give me the time of day because I was not a green card holder (these schools are usually heavily funded by the state, not necessarily a state school, a good example is Jefferson).
In the end, my international background helped at Columbia, and I don't think it either helped or hurt me at Tulane. By the way, Tulane is an international friendly school that everyone should apply to (an awesome school too, with a program in International Medicine and all).
Med school apps are the luck of the draw. Do your part, get good recommendation letters from people who know you, apply early - take a year off if needed to improve research skills or to solidify your commitment to medicine - then cross your fingers, send thank you notes and wait. Once your part is done, it is up to them to accept you or reject you based on or not on the fact that you are not American, there is nothing that you can do about it
An interesting thing to keep in mind is that usually the schools that take internationals are building their overseas reputation, forming "leaders in medicine," it is important to realize that in the beginning, it is a good clue on how to decide which schools will be receptive to you or not. If a school's mission is to form doctors who will work primarily in rural areas of their state: SAVE MONEY, DO NOT APPLY! I wish you all luck!!