If Hillary Clinton’s campaign thinks it has sewn up the black vote in the city, it has not visited the Gabaron Barber Shop on 116th Street in Harlem.

The men getting their hair trimmed as well as those wielding the razors took turns expressing strong support for Senator Bernie Sanders. Even the sidewalk near the shop has the likeness of Mr. Sanders drawn in chalk, the silhouette of his hair perhaps in need of a trim of its own.

“Bernie supports black people, plain and simple,” said Corey Smith, 30, a hotel worker in the midst of a shave. “I’ve seen the photos of him marching back in the day, and now I’ve seen him all over Harlem.”

Mr. Smith has an 8-year-old son and he said Mr. Sanders’s plan for free college tuition appealed to him. Besides, he added, he couldn’t get past Mrs. Clinton’s support of the 1994 crime bill signed by President Bill Clinton, which set lengthy prison sentences and flooded the streets with police officers.

Yacouba Konate, 28, Mr. Smith’s barber, an immigrant from Ivory Coast, is in the United States on a green card and is therefore not eligible to vote. Regardless, he’s followed the race closely.

“I don’t care as long as it’s not Trump,” he said. “I want to stay in this country.”

Manny James came to support Mr. Sanders after growing skeptical of Mrs. Clinton. “Hillary just goes around contradicting herself all the time,” said Mr. James, 26, a hospital janitor. “She’s trying to pander to black people, but it won’t work.”

He caught a glance of himself in the mirror and went on: “Bernie has been with us since Day 1. That man marched on Washington.”

Michael Killatt, 51, a highway maintenance worker wearing a Bernie sticker on his shirt, interrupted to agree.

“Bernie and I, we’re both from Brooklyn,” he said. “He’s the real deal. He’s been talking about helping the homeless and making school more accessible. I like that.”

His barber, Jesse James, 36, sighed at all the talk. “This whole thing just makes me wish Obama could run again,” he said. “They gave him a car with no engine, and he still managed to drive the thing.”

Manny James interrupted him: “Enough with the politics,” he said. “Pay attention to my cut.”