I just wrote about this issue but here's another useful piece on where Trumpism came from. This is a well-researched article by Zach Goldberg taking apart Adam Serwer's influential recent Atlantic article. As you may recall, Serwer at great length and with modest empirical backing essentially equates the entire Trump phenomenon to white racism. Goldberg shows just how modest Serwer's empirical case was using hard data and analysis. Goldberg concludes:
Highly recommended.All told, the evidence suggests that Trump’s election had more to do with economic disquiet, the fear that America is trending towards a culturally balkanized identitarian society (i.e. political multiculturalism), and a climate of PC that discourages voicing of concerns about either. We can debate whether these concerns are reasonable. But the hypothesis that they’re simply a guise for white bigotry and the continuance of white supremacy finds no support in the present data. In the end, it’s almost as if Serwer’s explanatory model conveniently includes only those variables that absolve the Left of any culpability in the Trump phenomenon.