I am at a loss to explain why anyone would buy investment property in any of the blue states, namely, Illinois, California, New York, New Jersey, and Connecticut.

But how each operates and scales is vastly different, an ocean apart. 

I go a little more blue collar outside of the city and can get 20% 

In particular Overland Park, Olathe, Lee's Summit, Blue Springs and North Kansas City.

Long term buy and hold RE in good locations is probably one of the lowest risk investment vehicles IMO, similar to blue chip aristocrat stocks except even less risky because even long-established companies can go out of business but real estate very, very rarely ever goes to zero. 

I'd suggest Ibonds, treasuries, and blue chip stocks with a good dividend.

I've had some blue collar ones all the way up to software engineers and everything in between. 

We decided to make a mini-working-vacation out of it and grabbed a STR outside of Blue Ridge. 

Look for areas with solid rental demand, typically in Blue Collar America, where BTR projects are particularly appealing.

I personally know several blue-collar millionaires from HVAC techs to plumbers.