This year Mr. Trump again carried the district. In 2022, Mr. Cartwright said, a Trump-style Republican in Pennsylvania’s elections for governor and Senate could win statewide. “Much of it depends on how life is going in two years,” he said.
Another region that reflected the shifts of recent elections, Saratoga County in upstate New York, was home to one of Mr. Biden’s most decisive performances in a pivot county. Mr. Trump won there by 3.2 points four years ago. Mr. Biden won by 5.4 points last month, for a total swing of 8.6 points.
Todd Kerner, the chair of the county Democrats, attributed the about-face to misgivings about the president by college-educated voters in the affluent suburbs of Albany, in the southern end of the county.
Jim Esterly, a retiree in Clifton Park, N.Y., was one of them. Four years ago, he said, he was taken by Mr. Trump’s TV persona from “The Apprentice.”
“I said, ‘Here’s a guy who’s a businessman,’” Mr. Esterly said. “He’s had businesses that failed, but he’s come back. I don’t know how he righted the ship, but I said running the country is like running a big business.”
Disillusion set in early for Mr. Esterly, 68, who had managed a municipal wastewater treatment plant. “He didn’t believe in climate change,” he said, citing the president’s withdrawal from the Paris accord. “When Covid hit, he was more than stupid, not believing his experts early enough, then saying, ‘Maybe we need to do something,’ then ignoring it.”
Mr. Esterly voted for Mr. Biden this year, and he had plenty of company in suburban Clifton Park. Mr. Biden won nearly 3,000 more votes in the town than Mrs. Clinton did in 2016. Mr. Trump increased his support there by only about 500 more votes.