“He says what the average person is afraid to say because it’s politically incorrect,” Mr. Marshall said about Mr. Trump.

Mr. Marshall worked at the Mahoning County Sheriff’s Office for 23 years, at the jail and on patrol — a front-row seat, he said, to the city’s dramatic decline. He watched as the professional classes emptied out, and as the city’s complexion changed: Youngstown, 74 percent white in 1970, is now about evenly divided between blacks and whites.

Drugs came in, he said. The murder rate soared. Young people were dropping out of school at 15 years of age, Mr. Marshall said, because they didn’t see what kinds of work a degree would get them.

“Where are they going to go, Taco Bell?” he asked. “That’s minimum-wage jobs.”

Seven years ago, he moved away, taking a job as a corrections officer. Today, his political views are eclectic. The Democrats, he said, “failed Youngstown”: During the steel days, they were the party of overbearing regulations, the ones who told management that they couldn’t open a second blast furnace. “That’s jobs they took away,” he said.