Andy Custer's box truck lumbers along the narrow streets of downtown Frederick on an ugly afternoon, rocking and groaning as it maneuvers around snow piles, past pedestrians, through late-day traffic.

From a distance, Custer looks like just another delivery driver on his route. His truck is one of many that jam the streets of Frederick this time of day, carrying bread and vegetables and beer to restaurants up and down Market Street.

But as Custer steps out with a load of blue plastic crates, his brisk trot generates a sound not heard in these parts for years -- the chime of glass milk bottles gently rattling. Heads turn, eyebrows furrow, and then looks of recognition dawn.

After a decades-long absence, the milkman's signature clink has returned in recent years to a wide swath of suburban Maryland. For the approximately 600 regular customers of Custer's employer, Middletown's South Mountain Creamery, it's the best thing to come along since . . . well, since bottled milk.

Two years ago, South Mountain Creamery started delivering milk door-to-door in Frederick -- the first such service in the county in 25 years. The company found enough demand to expand into Washington County and parts of northern Montgomery County. An independent contractor delivers South Mountain milk to customers in Howard County, and the company hopes to start delivering in Baltimore this year.

"We're almost at a break-even point," said Abby Brusco. She and her husband, Tony, run the creamery that produces the company's milk. "We're just starting to make a profit."

It hasn't been easy. Only one manufacturer, a Canadian company, still makes glass milk bottles. The machine that South Mountain uses to clean milk bottles is 30 years old, because nobody makes them anymore. Refrigerated milk trucks also are hard to come by. And without any local milk delivery business to study and model itself after, South Mountain had to learn a lot through trial and error.

"They're so friendly," said Gloria Johannessen, whose family of six moved to a new subdivision in Frederick from the Chicago area two years ago and quickly signed up for milk deliveries. "They're accessible. If you've got a question about an order, you can call. . . . And that layer of cream on top -- I hadn't had that since I was a kid."

Home delivery of milk began plummeting in the 1960s, with the rise of supermarkets and mass-produced milk from factory-like dairies. Families became more mobile, lives became more hectic, and the charm of the milkman could no longer justify the cost, for consumers or companies. Dairies began shying away from the expense of door-to-door deliveries. Consumers didn't want them, either.

Home-delivered milk from South Mountain costs $2.90 for a half-gallon, plus a delivery charge of about $4 a week. Supermarkets around Washington generally charge less than $2 for a half-gallon of milk.

"When people realized they could go to a grocery store and get the same milk and get it cheaper, they did it," said John Rutherford, a research analyst with the International Dairy Foods Association.

In 1963, about 30 percent of all milk sold in the United States was home-delivered, according to the U.S. Department of Agriculture. By 1971, the figure had dropped to less than 15 percent. By 2001, less than half of 1 percent of the milk sold in the United States was home-delivered.

The number of dairy farms in Frederick County, long a center of dairy production in the mid-Atlantic region, has dropped from 323 to 183 since 1992. Many of the farms have been replaced by subdivisions as the area has been flooded with newcomers.

South Mountain has found that the folks whose new homes replaced many of the dairy farms -- the new suburbanites -- have flocked to the milk-delivery service. They are people who want specialty products, who want better-tasting milk and the small-town ambience that attracted them to Frederick.

"It's kind of bittersweet," said Tony Brusco. "We don't want to see more farmers leave Frederick. But at the same time, every time a house goes up, that's a potential new customer for us."

Dairy industry experts say that a recent growth in home milk deliveries in some areas of the country probably has more to do with nostalgia and the finicky tastes of certain demographic groups -- middle- and upper-income suburbanites -- than with any broader trend. Nobody predicts a mass resurgence of home-delivered milk.

Potomac Dairy Service, a one-man operation, has been delivering to a few hundred homes in Potomac and Bethesda for nine years. But no dairies make home deliveries in the District or Northern Virginia.

While there have been no signs of a large-scale resurgence, several business across the country have managed to thrive on home-delivery sales.

Oberweis Dairy, based in the Chicago suburbs, has grown from about 3,000 customers in the mid-1980s to more than 45,000, scattered across Illinois and Indiana. Like South Mountain, the company offers specialty products that can be hard to find in a typical grocery store, including hormone-free milk and organic milk.

Nostalgia draws some customers in, as does the convenience, said Bob Renaut, the company's president and chief executive.

"Many of our customers haven't ever seen a glass bottle," Renaut said. "They were born after glass bottles faded away in the early '60s."

In the Washington region, as in most of the country, home delivery became almost nonexistent during the early 1970s. The last major home-delivery service in the District's Virginia suburbs, Shenandoah's Pride Dairy, stopped delivering in 1979. But South Mountain has taken a gamble that it can make the practice profitable again.

It is the only small-scale dairy in Maryland that processes its own milk, yogurt and butter. Like other such companies in the country, South Mountain has found that many of its customers are young families -- people with more disposable income than free time. For them, the quality and convenience of home-delivered milk justifies the expense.

"It's middle- to upper-income people," said Jim Carroll, vice president of Crescent Ridge Dairy in the Boston suburb of Sharon. Crescent Ridge has been delivering milk to homes since 1932.

"Moms are a lot busier nowadays than they were before," Carroll said. "They've got to make sure they can squeeze everything into the day that they can."

Staff researcher Bobbye Pratt contributed to this report.

South Mountain Creamery delivery man Andy Custer exchanges empty milk bottles for full ones during a stop at a customer's house in Frederick.Jose Marcelino Guzman washes bottles and fills crates for door- to-door delivery, a throwback to the day's of the neighborhood milkman. South Mountain Creamery owner Randy Sowers heads to change clothes and make milk deliveries to customers.