In the two years since Mr. Trump’s election, protesters and politicians on the left have lamented the erosion of values around tolerance and diversity. On the right, they have continued to mourn the loss of religious and traditional family values at the center of American life.

Ms. Hochschild identifies as a liberal herself, and after Mr. Trump’s election, she said one of the conservative voters she described in her book sent her an email.

“She said, ‘Well, I guess it’s now your time to feel like a stranger in your own land,’ ” Ms. Hochschild said. She acknowledges that she has felt this way of late, as she has watched President Trump declare the free press the enemy of the people and question the independence of the judiciary. “I had no idea we could come this far this fast and challenge things I thought were basic,” she said. “It feels like some pillars of our culture are being shaken, stress-tested.”

That is precisely the feeling she had described in Louisiana.