What Rust Belt?
Continuing in the "happens in some place" theme...
I am not a political scientist or statistician. However, I have seen quite a lot of the United States, and I am more than ever convinced that there is no 'Rust Belt' anymore. (People driving cars made in Tennessee and Georgia, you may agree.)
Like Northern England, the Great Lakes region once had a lot of heavy industry, and there are enough people still alive who remember that era that political consultants can be paid very well to fret about the Rust Belt Problem.
The only place I have set foot in that looked and felt like 'the Rust Belt' to me is Gary, Indiana, a shell of its former grandeur. If there was ever a place tailor-made for the words 'Make America Great Again,' I would have to say it would be 21st-century Gary. (My experience of the Detroit area is limited to the bright perky international airport outside the city.) And yet (Gary being 84.8% African-American might have something to do with this) in Gary's county, Lake County, Trump received less than 38% of the vote.
A vague approximation of Gary, I guess, may be Milwaukee, which has also lost much population in the last 60 years. Trump didn't get very far here either, despite a county sheriff who wants all citizens to arm themselves and throws accusations of 'penis envy' at his political rivals.