“That way of life has really evaporated,” said Jonathan Weinzapfel, who was Evansville’s mayor the year Whirlpool left, idling 1,100 workers.

And blue-collar workers are not the only members of the middle class being squeezed. Jeremy Marshall, who has a master’s degree and earns about $50,000 a year teaching at an elementary school, has long worked a second job — first mowing lawns, now as a home inspector.

After Indiana’s Republican legislature rolled back teachers’ bargaining rights and tied their pay to student test scores a few years ago, Jeremy said, he missed out on what otherwise would have been an automatic $12,000 raise. He said he voted for Mr. Trump, but in statewide elections he supports Democrats, who are union-friendly.

His workday is longer and more stressful than it used to be, he said. “I go home, and I’m mentally zapped. Everything’s data-driven. It’s always analyzing data, creating assessments to create more data.”

At Applebee’s, as the conversation circled around the complexities of trade, Brandon Marshall, once in favor of strict protectionism, seemed to shift his view. He considered how tariffs might strain Jeremy’s budget and threaten Troy’s job.

“It’s hard to say what would happen if we shut the borders off and had to start surviving on our own,” Brandon said.

“The thing about Trump, he never had to worry about a $15 tape measure compared to a $6 one,” he added. “He’s got good intentions. He wants to keep the jobs here. But if all those parts coming for Toyota cost more money to get here, is it going to turn jobs away in the long run?”