Speaking of higher education, everybody knows there's a strong correlation between support for Trump and the lack of a college degree. I think I know why this is, and it's not the extra education per se.
It's that many young people meet foreigners -- lots of 'em -- for the very first time when they go to college. When I was a Cornell undergrad in the 1970s, I had fellow students from practically every country in the world, but especially (pre-revolutionary) Iran, China and India. You quickly accept them as fellow students who just happen to look a little different and speak English a little differently (although that part could be a problem).
Many people without the benefit of a college degree, especially those who grow up, go to public school and live their entire lives in rural areas, never get that opportunity. And so they (can be made to) fear those they do not know.