A man knocked on Charlotte Ross’s door one morning in 1964 and asked the stay-at-home mom if she’d be interested in becoming a crossing guard at Alexandria’s new elementary school. She said she’d give it a try.

Nearly 50 years later, she’s still on that corner every weekday, at drop-off and dismissal, making sure little feet safely cross the street to James K. Polk Elementary. That’s her official job.

Her unofficial jobs include lending an ear to parents as they go through divorce or the loss of a spouse, bringing food when they’re sick and, from time to time, walking children home when their parents are in a bind.

“Heavens no, I don’t mind,” said Ross, 87, who lives several blocks from work and walks there twice each day. “My husband used to say I should put a sign on the pole saying ‘Charlotte Ross is open for business.’ ”

In Alexandria, crossing guards are employees of the police department, and Ross — once a fashion model at a department store — is the longest-serving member of the agency. By many accounts, the corner of Polk Avenue and North Pegram Street belongs to Ross.

“It’s her corner, there’s no doubt about that,” said Jim Schonberger, 52. Ross helped him across the street for the first time when he was in elementary school in 1969, then did the same for his sons, Lester and Charlie, when they attended Polk.

Slowly, and mostly by happenstance over the years, Ross has become a kind of backbone for the neighborhood. Each morning, parents and dog walkers stop by to visit her, turning her corner into a virtual cafe.

She offers things many people do not, her visitors say: She’s dependable, she’s a good listener and she doesn’t gossip. She fills in the gaps when her neighbors need a friend, an ear or child care in a pinch.

“She has quite a following,” said Anna Belle Fuller, whose daughters Ross helped across the street years ago.

One woman said when she was going through her divorce she couldn’t wait to see Ross each morning and unload about her troubles. Another man, a widower, opened up to her about the loss of his wife and soon made a habit of coming by for her company.

Ross runs the intersection with a firm hand, engaging people only when time allows. “Excuse me, you have to move back,” she instructs anyone who is blocking her line of sight.

“Here you go,” she directs, nodding her head when it is time to cross.

In Alexandria, crossing guards are 10-hour-a-week civilian employees of the police department. There are 25 of them. Most work on a corner for a while, but some long-timers become part of their neighborhoods’ fabric. Ross sets the standard for the latter, said Alexandria Police Chief Earl L. Cook.

“If I had 10 more Mrs. Rosses, I’d sleep a lot better when I think about the safety of our schoolchildren,” said Cook, whose mother was a crossing guard in Arlington for 18 years. “Let’s just say the citizens are getting a lot more than they’re paying for.”

Her corner has seen its share of change and news through the decades. A horse farm gave way to single-family homes; a woman was found dead in the wooded area across the street in 1977, murdered by a serial killer who later confessed; children grew up, went to college, had babies.

On a recent morning, as she dropped her daughter off at kindergarten, Mary Newell recalled how when she was a student at Polk she would wait with Ross for 15 minutes each afternoon. Newell’s mother wasn’t able to make pickup on time, so Ross gave her a hand, free of charge.

“It was a safe place to be,” said Newell, 27.

Another resident who stopped by that morning, Emmy Henard, 68, recalled that when she was laid up after ankle surgery a few years back, Ross brought her a chicken lasagna . A man who goes walking with his wife each morning said if his wife isn’t with him, Ross will ask why.

Ross, a grandmother of four and great-grandmother of two, doesn’t like to talk about helping her neighbors. She prefers to talk about her job. The way to be a successful guard is to be on time and to dress for the weather, she says. She has no plans to retire.

Ross helped her own children cross the street when they attended Polk, and she worked through her grief when her husband died 20 years ago and when her boyfriend passed away recently. She took only a few months off when she was in a car accident a few years ago while on vacation and lost her left hand. She has a prosthetic.

“It doesn’t bother me a bit,” said Ross, who grew up in Arkansas.

But when she was gone for those months, the community was abuzz.

“The neighborhood was really worried about her,” Schonberger said.

As for why people share their problems with her, Ross said she thinks they talk to her simply because she’s there.

“Most people don’t want to hear other people’s problems,” she said. “I don’t solve them. I just listen.”

Truth is, she confides, she needs the children and their families as much as they need her.

“It’s my therapy,” she explained.