@Bangkok ready d1 Please see above for the kind of intellectual divide we're talking about.
Obviously, the issue is complicated. But, basically, with the modern economy, the best and brightest from rural areas tend to get advanced degrees and then move into cities where they can get good-paying jobs that require those degrees. Someone from Population-500, Kansas who gets into Harvard to study molecular biology is obviously not likely to ever return to rural life because it doesn't have any of the institutions or employers that need their expertise and can compensation them. So they move to Chicago, or Seattle, or Atlanta, etc.
The result is a brain-drain of sort, where rural America is much less educated and is also much less exposed to the cultural diversity of urban areas. And that cultural and racial diversity scares them very much, it seems.
This intellectual divide has been massively aggravated by the internet age, particularly with rural communities that did not have great internet access until fairly recently. They are not versed in deciphering propaganda from actual reporting, which to be fair is quite difficult and takes a lot of exposure to the internet to really get a hang of things. This has resulted in massive disinformation bubbles forming across rural communities, where large amounts of these communities really believe in outright falsehoods, like that the Clintons are mass murderers, Bill Gates is using vaccines to microchip people, there's an impending white genocide, etc.