This year, just as she has for the past three decades, Shirley Todd will begin each autumn morning standing sentry at the street corner she can see from the window of her Purcellville home. There, she will shepherd the town's children across the street to Emerick Elementary school.

Todd, 73, a former preschool teacher who raised six children of her own, is one of Loudoun County's longest-serving crossing guards. When she started in February 1975, at a salary of $3 a day, only a few children came to that intersection each day. But now as many as 100 students -- including the children of children she crossed years ago -- depend on her for safe passage twice each day.

Todd knows the children by name, and they know her. All these years, she's never tired of getting to know the youngest members of her community.

"I like being around children, and I like keeping in touch with what's going on," Todd said. "It's a good way to meet newcomers to the community."

But while the number of children -- and cars -- is growing fast in Loudoun, it's been harder and harder to find people like Todd, said Willy Stevenson, who supervises crossing guards for the Loudoun Sheriff's Office.

Stevenson began heading the program in 1986 and had no problem finding takers. "Back then, people were lined up," she said. "If you had a vacancy, you usually had two or three people in line to get it."

But things are different now. Fewer people seem to have the time to apply for, or interest in, a job that requires about 70 minutes of work each weekday and brings in $12.63 to $17.05 an hour.

Loudoun has space for 50 crossing guards and has about 10 open slots, Stevenson said. Little River Elementary School in South Riding went without a permanent crossing guard all last year, and for much of that time Stevenson handled the intersection herself. Most school days, she said, she had to call in deputies to fill vacant slots across the county.

And it's not only fast-growing Loudoun that needs crossing guards. Fairfax County police are hiring, and Alexandria police Lt. Paul Story said his department has vacancies, too.

"I really admire the people who are willing to do it because most of them are doing it for more than the money," Story said. "It's a real valuable job because, after all, they are responsible for the children out there."

Helen Adams, 52, who is preparing to begin her seventh year as a Loudoun crossing guard, said it's a perfect part-time job. Adams wants to earn a little extra money but doesn't want to work long hours. She doesn't even mind trudging through rain and snow.

For Adams, who has worked near several schools in eastern Loudoun, interacting with the children is the best part of the job. "It keeps you young," she said. "They make me laugh."

Adams said she is also pleasantly surprised by the reactions she gets from parents and other drivers. "Everything around here is so rush-rush," she said. "But you'd be amazed at the drivers who stop, roll down the window and say, 'We're so appreciative.' "

Stevenson puts it this way: "It's not for the money; it's a community thing."

Todd has had children pick flowers for her on their way to her corner. And at the end of the day, they sometimes bring her a cookie, or a slightly squished cupcake, left over from a school party. The kids confide in her when they are having a bad day and cheer her up if she's having one.

Todd's going to keep her post for now, but there may soon be a vacancy sign at her beloved corner. "I don't have plans right now to say this is my last year," she said. "But I won't say it's not, either."