The poor white sharecropper was no better off economically than the poor black sharecropper but for that privilege. The white sharecropper knew he was better than Black people and his status was even reflected in the way the rest of society treated him.
For example, in the community I grew up in, "Driving While Black" citations were a favorite sport of the local police. They'd harass black pedestrians too, treating them as if they didn't belong there, full on Nazi "Papers please!" There were also a few embarrassing (and costly!) lawsuits against the police for violently arresting the very first Black or Hispanic person they encountered after any crime that was purported
to be committed by a Black or Hispanic male.
Another example: During the Dust Bowl and Great Depression years "Okie" was not a term of endearment in California. I used to frequently encounter elderly people in that community who were still bitter that California growers hadn't fired their Mexican-American workforce the instant these white Dust Bowl refugees showed up on their doorsteps. It's not that these growers were not racists, most of them were, but why would they replace skilled Mexican American workers, experienced in irrigated agricultural practices, with unskilled refugee labor who'd been so silly as to trust in God that it would rain?
I first heard the words "White Trash" from one of my grandmas born in San Francisco just after the Great Earthquake, to an affluent California dairy family. Some of the roads where I now live are named after my great grandfather's cousins. My wife's Mexican-American father was born in a farm worker's tent near a small money pit farm my parents once owned (which is now part of an ugly wasteland of million dollar mini-ranches and MacMansions... my parents sold too soon.)
Undeniably a number of Trump voters were impoverished white people who couldn't understand why they'd been left behind with all those other people.