The United States is separated into two mutually distrustful political camps, but in Erie, the camps sit side by side — friends, neighbors and family members who live and work together yet cannot fathom why the others believe the way they do. These days, Erie is carpeted with campaign banners and signs, one yard often facing off against the next, a battle posture borne out by national surveys finding the highest share of Americans in decades — more than four in five — who believe the outcome of the election “really matters.”

But as the days lurch toward November, there is a remarkably bipartisan sentiment: dread.

“Just stick the knife in,” Marlay Shollenberger, 33, said of the looming election and all of the terrifying discord that could accompany it. “That’s kind of where I’m at.”…

Mr. Hawes, 47, rues the day he sold off most of his guns. His unease about November is one of the only things that he and his stepfather, Tom Ulrich, 73, a die-hard Democrat, agree on regarding the election.

“There could be a lot of trouble on the streets,” Mr. Ulrich said. “Never mind the courts, I’m talking about on the streets.”