Stats on Rental Market Saturation?

[Neill Dorn]

Hi, I'm brand new to this site. I've been directing my investments exclusively into stocks for the past 10 years, and am eager to experiment with property. I live in WA state, but my target markets are in the upper Midwest where I grew up. The prices are ridiculously low. I realize lots of people are moving away from the prairie states, but (of course) a lot will stay.  

Before I drop a pile of cash into one of these houses, I'm looking to learn from others. Do you know how I can assess demand for rentals in a given city?  I'm imagining that there are stats of how many properties are on the market, vacancy rates, percent of population who rent vs own, etc.  It's there a convenient way to find that info?

Thanks in advance. I look forward to learning from you all.

Neill