Shirley Todd is something of a neighborhood institution in Purcellville, a fixture on the corner of South Nursery Avenue and Orchard Drive in front of Emerick Elementary School.

Todd, 75, has been Emerick's crossing guard -- shepherding students across the street twice a day every weekday during the school year -- for more than 30 years.

Residents refer to the intersection as her corner, as in, "Hey, that lamp light on your corner is out," she said. The fact that many people count on seeing her there every day was underscored when she was on medical leave for two months in 2002 after hip replacement surgery. At the time, her son Wayne ran a baseball program for youths and discovered that some of his players were Emerick students.

"He said, 'Oh, you must know my mother, Mrs. Todd, she's the crossing guard there.' They said, 'Well, she's dead,' " Todd said, laughing. "That's how it is with kids: If you're not here, you're dead."

She is, for the record, healthy and vibrant -- a white-haired, bespectacled grandmother who appears rock solid and sporty in her uniform brown trousers, white shirt and orange vest, holding vehicles at bay with a whistle and an upright palm while children scurry across the street.

Barely visible through the fluorescent orange mesh of Todd's crossing guard vest are three pins fastened to a pocket of her shirt -- one for her 15th anniversary as a crossing guard, one for her 20th and a third given to her on Monday by the Loudoun County Sheriff's Office, which employs school crossing guards, for her 30th anniversary.

This one, she noted with some embarrassment, has a tiny diamond embedded in it. "That's where your tax dollars are going," she joked Tuesday.

Todd is determinedly humble when it comes to discussing the hullabaloo surrounding her long tenure as a crossing guard, which began in February 1975. "It's a job, and plenty of people work 30 years at a job," she said. "I don't think it's that big a deal."

Except, perhaps, for the fact that Todd's presence on "her" corner engenders a sense of community, a rarity in an era of increasing isolation from neighbors. Todd and her husband, Stanton, now retired, live just two houses down from the intersection.

"It's a good way to meet people," she said of working as a crossing guard. Mothers stop to talk, and Todd asks them about their older children -- the ones who have started sixth grade at the middle school and no longer cross her daily path.

Donna Griffin no longer escorts her son, Tim, to school. Now that he is a fifth-grader, she said, "he won't let me walk him anymore." But she sees Todd every morning when she walks the family dog, Ike. On Tuesday, Griffin, a real estate agent, paused to discuss the continued spike in local real estate prices while Ike, whom Todd gives a doggie biscuit every morning, gobbled up his treat.

"We're always out here chatting," Griffin said of Todd. "She's awesome."

Willy Stevenson, program manager of the sheriff's crossing guard unit, said it's "nice when you find people who are in your own community. It's a very community-oriented job."

It also helps to love children, Stevenson said. Todd, mother of six and grandmother of 13, ages 5 to 26, is arguably a maternal maven. A stay-at-home mom who ran a child-care business, she signed up for the job at a friend's suggestion when her youngest child entered preschool.

Thirty years later, not much has changed, she said. Sure, the pay is more -- she earns roughly $17 an hour for two hours of work compared with $3 a day in 1975 -- and the number of children she guides across the street each day has grown from five to nearly 40, but "kids are kids," she said. "They're friendly and you can cut up with them a little. They're fun."

They smuggle her cupcakes and cookies from school parties and tell her about their vacations and homework assignments. Some are unfailingly polite -- "Thank you! I can't believe I almost forgot to say thank you!" one boy called back after Todd stopped traffic to let him through -- and they all appear to follow her lead respectfully.

There are second-generation crosswalkers, too. Christy Bailey, 30, was escorting her 5-year-old daughter to school when Todd called out hello. Bailey, who lives on the street she grew up on, was one of Todd's earlier charges.

"This is when you really begin to feel old," Todd said. "When you've got children of children."

Helping children twice a day for an hour each is a lifestyle that suits Todd, who is outside at 7:20 each morning and at 2:30 each afternoon, regardless of weather. If it rains, "you wear a raincoat and hope it doesn't leak," she said.

These days, it's a tougher job to fill. According to Stevenson, the manager of the crossing guard unit, there is high turnover because the job is only part time, and the twice-a-day availability makes it difficult to schedule a second job. One position in South Riding has been vacant for 18 months.

"As for the Shirley Todds of life," she said, "I guess it remains to be seen whether the ones that have been here for a while will stay 30 years, but I don't see that happening so much anymore."

Shirley Todd has been a crossing guard at Emerick Elementary in Purcellville for more than 30 years. "I don't think it's that big a deal," she says of her long tenure.