I do a decent Boston accent, and an excellent Kennedy/Cape one. and I am from Ontario, though I have been here off and on for about 13 years, total. I also do a really good Georgia one. These are, I note, places that I am not from but that I have lived in for extensive periods of time, and I have a pretty good ear.

The one I have NEVER been able to do is Minnesota. Cannot do it to save my life.