I’m as predisposed to focus on rampant racism in the electorate. But it is not new, so unless there is something that inflates it, it cannot explain voting trends. You could say Republican rhetoric ramps it up, by hyping the immigrant “problem.” (I may be alone in claiming immigration is absolutely NO PROBLEM except for the hardships endured by those who need to immigrate.)
The race thing seems to be receding in the MAGA universe. It is mostly xenophobia, transphobia, and homophobia. As such it appeals to many POC, who seem to be responding more favorably to Trump. I haven't read Heather McGhee’s book, but from what I’ve heard about it, I am not motivated to do so.
Historically racism, of course there was plenty of it around, did not block progressive politics, say, in the 1930s. Racists voted for Jesse Jackson and Barack Obama. Southern states after 1970, after the blossoming of civil rights legislation, had a passel of Democratic governors and senators.
Last month, Trump won in the border counties of Texas. I live in a very white, Trumpey part of Virginia. I did a bit of canvassing and encountered a black man, my guess was working class. When I identified myself, he said, "I'm a patriot." I responded, "So am I." (LOL). It did no good. I think he just wanted to fit in with the neighborhood.
A thing from political science, and I'm no political scientist, I got it second hand, is "cycling." People dissatisfied with their lot just reject whoever seems to be in charge. Doesn't much matter what either side says. Doesn't matter that Trump had no solutions. Just throw the bums out. I think that explains the election. As long as so many are disengaged from politics, it will keep happening.
People I know who have no use for Trump and no homophobia maintain that the Democrats or "the Left" are all about letting boys use girls' bathrooms and compete in girls' sports. I don't understand why they say this, since clearly that sort of discussion plays little part in the standard Democratic Party appeals, much less from Bernie Sanders. I still keep hearing it. It drives me nuts!
I am skeptical that going full Bernie won't necessarily solve the puzzle, though it is my default posture because I have nothing better. Insofar as immigration is a real problem as well as a perceived one, I don't think it's going away. Climate change and political instability will likely make it worse, not just here but in Western Europe too.
In short, I am unpersuaded at race or anti-racism being the skeleton key that unlocks our predicament. Indeed, by rights Tom Frank's Kansas should have stayed populist if race was the deal, since it is mostly white. States where immigrants have little presence went big for Trump.
I think you will find in the data that rural counties where people of color are LEAST present are typically the MOST racist in their voting pattern. When there ARE some neighbors of color their reality is less frightening than their reputation as portrayed on Fox, for example. But there is another dynamic which explains why the whitest counties are the most racist. Their white residents are so racists that no blacks dare migrate to live there! I know counties in Oregon and Idaho like that. My guess is that both stories are true.