Chances for a Canadian?

I am currently a Canadian high school student looking to enter the world of finance in the United States, and will apply to American universities (Hopefully in the Ivy League) when the time comes.

My main question is, just how difficult would it be to find an internship and a job after graduation (Especially since the company would have to sponsor me, etc.), and would an American job be much more rewarding than a job in Canada? Do note that i am willing to go through a lot of work in order to become a U.S citizen over the course of my life, and am aiming to leave Canada as soon as i graduate high school (And hopefully never come back). Is it true that HR departments are too lazy these days to sponsor Canadians?

Also, is a Wharton undergraduate degree (Or any other economics degree from the Ivy League) the only possible way for a Canadian to break into the U.S world of finance?