Educated people were coming in. But something else was happening: Educated people who had been here for a long time were changing. By the early 2000s, white voters without a degree were drifting toward the Republican Party and white college graduates were going the other way. By 2017, the pattern that Pew identified in 1994 was practically reversed: Just 42 percent of well-educated white voters leaned Republican, while 53 percent preferred the Democrats.

“There has been a dramatic realignment among white voters by education,” said John Sides, one of the authors of “Identity Crisis,” a book about the 2016 election. “It is not an aberration. It is now a durable new feature of our politics.”

Party preference does not shift suddenly, but slowly as turnoffs accumulate. Mr. Levitt kept voting Republican for years, even in 2008 when Kent County went for Mr. Obama. Mr. Levitt may not have voted for him, but he was glad that someone was trying to do something about health care and climate change. And while he has been hunting with his son, he saw nothing wrong with an assault weapons ban, something Republicans opposed.

The beginning of the end for Mr. Levitt was the Tea Party movement, the populist surge whose stated foe was government spending, but which had an angry ethnonationalist edge.