Hi Randolph! Canadian here, looking to invest in the US - so opposite of what you're trying to do! Haha. The only reason I'm not investing in Canada right now is because in general, it's very expensive. However, one market I'd like to get in to is the Windsor, Ontario market. It's right across the bridge to Detroit. They're planning on building a second bridge to Detroit and have plans to build a mega hospital in the city.
Southern Ontario as a whole is very hot, but most places you won't see cash flow and it's more of a speculation game, which is very risky for investors. As an American, you are at a 35% advantage as your dollar is about that much stronger! Be aware of provincial taxes, though. Eastern (Atlantic) Canada has some hot markets and even though Canada and US have a tax treaty, you'd be subject to that province's income tax rate...which is very high in Atlantic Canada provinces.
If you're really interested in this route though, definitely contact a Canadian/American cross-border specialist (attorney/accountant). On the Canadian side, I can use TD Bank or RBC Bank to obtain a mortgage in the US using my Canadian financials because these banks operate in both Canada and the US. I would guess it would go the same the other way, if you're looking to get a mortgage....but definitely call them and ask!
Lastly, there are a few nuances between Canadian real estate and American real estate...1 major one is that in Canada, we only have mortgages with an interest rate period of 3,5,7,10 years with an amortization period of 25 years - kind of like what you would call an Adjustable Rate Mortgage in the US. We do not have fixed rate mortgages for 30 years. At least not with the major banks or credit unions! Happy searching!