That is because of economies of scale. It is not possible to get a U.C. Berkeley in every one of the 17,000 towns the US has. Not even big cities will be getting U.C. Berkeley. Aside from NYC and Boston and Pittsburgh, there isn't any other city that has a comparable Top-5 engineering school.
Same for Tesla factories, you cant have a factory in every one of the 17,000 towns.
I'm not sure how Trump is helping these towns, but the Dems did offer solutions, more fundamental solutions. Like better access to education so new graduates could qualify for better jobs. These problems have been created over a generation and wont be solved with a simple travel ban or what not, they will be solved with education and empowerment.
Secondly, Dems have tried hard to get a better health-care system. Being an entrepreneur I understand how critical this is -- without healthcare I would not take risks, not with a family. I'd stick to my job to just get health benefits. Having a portable health plan is also critical to allowing people mobility, hopefully upward mobility.