Trump’s appeal seems to be in high school educated whites, so I’d guess states with a higher % of them and a higher % of people who work(ed) in manufacturing would see more Trump support as opposed to a candidate like Jeb or Cruz.
The Rust Belt, like you said. A normal GOP candidate couldn’t fire up the coal workers, steel workers, West Virginians, rural Pennsylvanians the same way. That is the region where anti-establishment, anti-free-trade, anti-globalism, anti-elite sentiment is strong.
I feel like Trump is going to win Ohio. I know plenty of educated white guys who are voting for him too. They will help the uneducated angry white guys tip him over.