Before I moved to Ohio, I had no concept of 'middle America' - the part that's driven by factories and industry. I lived the first twenty-three years of my life in central Minnesota, where everyone worked in malls, food service, offices, schools, etc etc. Factories? What are those?
Then, I moved to industrial Ohio. Half the warehouses on old main street have been abandoned, windows broken out and bricks falling away. Many of the factories that once thrived are now gone. In my small town, there are a dozen dollar stores, three 'discount' groceries, and countless Cash Advance establishments. Everyone works in a factory - or, did, until the factories left. Sure, there's work to be found, if you're willing to accept $7/hr for manual labor, 10-hour days.
In my area, factory middle-class doesn't exist anymore. Something collapsed... factories closed, left America, replaced people with smarter machines. When I left my job at a local factory, they'd just replaced several assembly lines with new machinated processes. Entire lines that had been staffed by dozens were now run by four people. That's progress, I suppose.