This old town on the Eastern Shore is so quiet, one local said, that someone could set up a cot on the main drag, Market Street, and sleep all night without being disturbed.

Even at midday, the town hardly bustles: There are about 3,000 people here, just enough to support a downtown with two consignment shops, a restaurant and a few other stores.

But real estate developers see something more in this Caroline County hamlet about 30 miles southeast of the Chesapeake Bay Bridge. They believe it could be a magnet for retiring baby boomers and have persuaded the city to annex enough property for 3,000 new houses.

All told, developments here could eventually bring a surge in Denton's population, Mayor James Bradford Horsey estimates, creating a city of 15,000, complete with shops and movie theaters.

"It's the biggest change I've seen in my lifetime," said Horsey, 69, who has lived through the end of Denton's railroads, the closing of the town's famous Double Dip ice cream parlor and the day in 1976 when the bridge over the Choptank River collapsed.

There are places like Denton all across the Eastern Shore now, facing a sudden real estate boom that could flood their towns with new residents -- in some cases, doubling their population.

Though many are optimistic that the new residents can reverse decades of decline, some people here are wondering how much growth would be too much, overwhelming their infrastructure and their small-town culture.

"I don't know where everybody's coming from, or where everybody's going to work or how it's going to work out," said Tracey Gordy, who works for the Maryland Department of Planning and is helping small communities prepare for the development.

"But," Gordy said, "it's going to be an interesting time here on the Shore."

Development has been an issue on the Eastern Shore -- the finger of land that is also called the Delmarva Peninsula -- at least since the Bay Bridge was built in 1952. In the 1990s, retirees began to discover cheap land and quiet living here, still within driving distance of grandchildren in Washington, Baltimore or Philadelphia.

From 1990 to 2000, census figures show that in one Eastern Shore county, Talbot, the number of people older than 60 increased by 28 percent. That was the highest growth rate in any Maryland county, with second place taken by Worcester County, home to Ocean City.

Talbot's hub is Easton, a town on Route 50 where developers started building large subdivisions in the late 1990s. The result has been a new phenomenon: traffic jams, which clog roads so badly that volunteer firefighters have had trouble getting from their homes to their engines in an emergency.

In the past two years, development across the Eastern Shore has hit another gear. Developers say they anticipate attracting retiring boomers from along the East Coast. Maryland's "smart growth" laws give developers incentives to build around existing towns, allowing more houses on each acre and better access to state money for roads and sewage treatment.

Nearly any town will do, so they've planned many of these developments in the Eastern Shore's interior, in burgs that are not on the bay or the beach.

In the town of Trappe, there are plans to add 2,300 homes to a place that now has 1,100 residents. Queenstown, with 617 people, could grow to more than 2,200 residents.

The trend also extends south to Virginia's Eastern Shore, where the town of Cape Charles could grow from 1,100 people to 7,100 when developers are through. And northward, on the Delaware end of the peninsula, is Bridgeville, where construction has started on a development that could add 2,000 homes to a town of 1,454 people.

In most cases, towns have not given the final go-ahead for these developments, and they might take 10 or 15 years to be completed.

Still, "it's a huge bulge moving down the snake," said Robert J. Etgen, executive director of the Eastern Shore Land Conservancy, a group that's trying to preserve open space on the peninsula.

For at least 30 years, retirees across the country have been turning to small rural towns instead of large developments in sunny states, said Calvin Beale, a senior demographer with the U.S. Department of Agriculture. But Beale said he could think of only two examples, both counties in Florida, where the growth in retirees was so dramatic as to double the population.

Environmentalists worry about the effects of development on this relatively pristine peninsula, run through with forests, and rivers that flow to the Atlantic Ocean and to the Chesapeake.

Longtime Eastern Shore residents also worry about the effects on their everybody-knows-everybody culture, which seems almost as ancient as the trees.

Margo G. Bailey, the mayor of Chestertown (population 4,700), said her town is still so tight-knit that employees at the movie theater call her at home to see whether her young daughters have permission to see a particular movie.

To Bailey, the growth of suburban-style developments in nearby towns is downright scary.

"I was absolutely flabbergasted at the uniform monotony of those homes. . . . They're 4- or 500 various colors of beige, two-story, soulless -- and I mean they are soulless -- homes," she said. "It's absolutely dreadful. It has nothing to do with this place."

Centreville has already felt the brunt of new growth. Unlike the tall century-old homes that line its old street grid, Centreville's new houses are modern, on lawn-lined and windy streets. They look as if a tornado picked up chunks of Columbia and carried them whole across the Chesapeake.

Retirees Gaye and Tom Baker recently sold their house in Arnold to move to a development in Centreville called Symphony Village. Gaye Baker said that a home there was selling for $300,000, when a similar house would have cost $700,000 on the west side of the Bay Bridge.

"It's just a little slower pace," said Gaye Baker, 56, whose home won't be finished until August. "It's just so hectic on this side of the bridge."

When the new homes came to Centreville, so did a shopping center with a Food Lion and a Domino's Pizza. There was also more traffic in town and increased pressure on the schools, because some of the new homes were occupied by families with children.

But the biggest impact was on the town's aging sewer plant, apparently overloaded and dumping raw sewage into a creek that flows into the Chesapeake.

The state and the town agreed on a moratorium: No more building permits would be issued until a new plant is built. The town's voters threw out the old council president and elected a newcomer, Mary T. McCarthy, to his seat on a slow-growth platform.

McCarthy, who moved here three years ago to escape the bustle of Frederick, said she hopes Centreville can be a warning to other places on the Eastern Shore.

"If it helps some other town," she said, "then I'm glad we were able to be an example."

Some towns are trying to heed the example. One of the best-prepared seems to be tiny Vienna, Md., a town of 300 people whose mayor is Russell B. Brinsfield, a University of Maryland administrator who has worked for years on land preservation.

Brinsfield said any developments here will be built on extensions of current roads, such as Horseman and Church streets, so old and new residents will at least have their street names in common. Also, he said, the new development won't be called "Vienna West" or something similar. It'll just be Vienna.

Somewhere between Centreville and Vienna on the development curve is sleepy Denton, where the first signs of development are starting to show.

Last year, construction started on the biggest development in Denton's history, a collection of townhouses and houses called Mallard Landing.

These certainly do not follow the Vienna model of preserving the old street names: They will have such bird-themed monikers as Blue Heron Drive and Ruddy Duck Court.

A far bigger development could soon be built in what's now referred to as West Denton, just across the Choptank from downtown. Robert D. Rauch and the Vienna, Va.-based developer Allen & Rocks want to build 3,000 houses where farmers now grow soybeans, corn and wheat.

"These people, they're going to eat out," said developer Nicholas P.H. Rocks, forecasting the development's economic impact as he bounced through the farmland last week in an sport-utility vehicle. "They're going to need doctors, lawyers, insurance agents."

But, in old Denton, many people are dubious about their future in a metropolis of near-retirees. Even the head of Caroline County Economic Development Corp. thinks they might be a plague.

"The first thing they're going to do is take over the town government. And the second thing they'll do is take over the county government," said J.O.K. Walsh, who is also head of the county's historical society. And don't think these empty-nesters will vote for school funding, he said.

At the Market Street Cafe, downtown Denton's only restaurant, Bob Borkowski said the changes are already apparent in new people around town.

Borkowski, who moved here from Baltimore 14 years ago, said he's alarmed by the new faces, new stores and traffic -- signs that the rat race of urban life has followed him here.

"The way of life we came to like, and the reason we came down here, is leaving," said Borkowski, 50.

"Look what it did to Centreville," said Brenda Durren, who moved to Denton three years ago because she found Centreville overdeveloped.

Durren said she fears a vision of Denton's future might be found in the area near the Route 404 Bypass, where an Arby's, a McDonald's and other fast-food restaurants now stand.

"It's an exit!" she said, not a town.

Robert D. Rauch, above, and developer Allen & Rocks envision 3,000 homes in West Denton on what is now cropland.Denton Mayor James Bradford Horsey looks over a brochure advertising Mallard Landing, a new development on the town's east end.

Denton, a town of 3,000, could eventually grow fivefold to 15,000 people. Some residents hope that older sections also might be rejuvenated.