As Ms. Dinezza observed, “he shops for himself, does his own laundry, pays his own bills — it’s crazy. He’s just in the right state of mind.”

“You hear about all these people asking, ‘What medicine can I take, what food can I eat, what anti-aging cream should I use?’” she said, “and he’s doing it with none of those things.”

As hairstyles have changed over the decades, Mr. Mancinelli has adapted. “I cut them all,’’ he said, “long hair, short hair, whatever was in style — the shag, the Buster Brown, straight bangs, permanents.”

Some customers have been coming to him for well over 50 years, having gotten hundreds of haircuts.

“I have some customers, I cut their father, grandfather and great-grandfather — four generations,” said Mr. Mancinelli, who has six great-great-grandchildren.

His son, Bob Mancinelli, said: “Some of his older customers, he helps them in the chair. He’ll say to an 80-year-old guy, ‘Listen, when you get to be my age. ...’ They love hearing that.”

Jen Sullivan, a stylist who works the chair next to Mr. Mancinelli, is all of 20.

“It’s just amazing that he still works full time,” she said. “Weekends here can get crazy — even I get tired of being on my feet — but he just keeps going.”

Mr. Mancinelli said he was born in 1911 near Naples, Italy, and emigrated with his family when he was 8, joining a relative in Newburgh, N.Y. He was one of eight children — “I’m the only one left” — and went to work at age 11 in a local barbershop. By age 12, he was cutting hair and dropped out of high school to cut hair full time.