Midge Teahan was having none of it when her daughter first suggested she move from Hagerstown to a Prince William County active adult community where every resident is on the far side of 50.

“They’re all old people there,” she recalled saying. “I don’t want to hang out with old people.”

Despite her initial misgivings, Teahan liked what she saw at a gated development called Heritage Hunt in Gainesville, and moved into a community that now numbers more than 3,000. Teahan, 74, is a busy member of resident groups built around travel, wine and mah jong.

Thanks to residents such as Teahan, Prince William County is becoming a regional retirement mecca, a small-scale version of Florida on the outskirts of Washington.

The share of residents who are 65 and older has risen much more sharply over the past decade in Prince William than in other suburbs. Their ranks have declined slightly in the District and in the Washington region as a whole.

Friends from left, Ron Skinner, 68, who has lived at Heritage Hunt for 10 years, Russ Ruppert, 75, 11 years, Rand Jones, 62, 7 years and Bob Kelley, 62, 10 years, gather on the balcony of the clubhouse after a round of golf on Thursday. (Katherine Frey/The Washington Post)

Prince William’s allure to older adults has implications beyond the county’s borders. The federal workforce is packed with baby boomers approaching retirement. Ten percent of the region’s population already is 65 or older, and 11.5 percent is between the ages of 55 and 64. Nobody knows how many will sell their homes and decamp for cheaper retirement havens better suited for fixed-income living. But less expensive alternatives to high-priced Washington are developing on the fringes, in places such as Prince William County.

An outer suburb once considered appealing mainly to young families, Prince William in recent years has seen the construction of several new housing developments restricted to residents 55 and older. Land costs less than elsewhere in the region, and developers have created sprawling gated communities for “active adults,” built around golf courses and clubhouses. Their presence has helped Prince William leapfrog over Montgomery County in median household income.

The communities have been an economic boost to places such as the Gainesville area, where Prince William Hospital is building a 60-bed facility and small strip malls with stores, restaurants and doctors offices have sprung up.

But the rapid demographic change may signal an upcoming shift in priorities for the county, particularly as members of the Me Generation turn their attention inward.

“They have a lot of disposable income, so they go to restaurants and buy stuff,” said Bill Vaughan, Prince William’s chief economist and demographer. “But some don’t have much interest in education. They don’t have kids in the household, and their focus is not on how good are the schools, which make up the biggest part of our budget.”

If past behavior holds up, most of the region’s older population will stick around. In a pattern that has held firm for decades, most older Americans do not leave the area where they spend their working lives and raised their families. That has been a durable pattern, even in a transient region such as Washington, where many people have relocated from other places.

An AARP analysis of census data showed that nine in 10 older adults nationally were living in the same communities where they raised their children and built their lives. Proximity to children, grandchildren and friends is key.

“Folks who have been living and working here for a number of years may find themselves surprised at the roots they’ve developed,” said Amy Levner, who specializes in housing and family issues for the AARP. “The lure of moving out fades over time.”

In this region, the phenomenon has been most pronounced in Prince William County. In 1990, 3 percent of the population was 65 or older. It rose to just under 5 percent in 2000, and more than 7 percent in 2011, according to census figures — a jump of 48 percent in the past decade alone. Vaughan estimates it is close to 8 percent now, although the county still has one of the youngest populations in the region.

Although some of the rise in older adults is the result of the first baby boomers edging into retirement age, Vaughan said, most of it stems from the active adult communities built in recent years.

The county Web site lists six developments of ­single-family homes and 12 apartment complexes that are reserved for people who are 55 and older. They are scattered throughout the county, from Four Seasons Historic Virginia in Dumfries to the Regency at Dominion Valley in Haymarket.

Heritage Hunt was the first, and today is the largest, with more than 1,800 homes, condos and duplexes. It’s built around an 18-hole golf course, and little green signs warn motorists to look out for golf carts. Fliers in the lobby advertise luau parties, Cinco de Mayo get-togethers, plays and concerts, all held in a grand ballroom that doubles as the development’s voting precinct on Election Day.

The houses are designed for aging in place. Although most are two stories, they have a master bedroom, a full bath and a laundry room on the ground floor.

“There’s a real market in Prince William for that kind of community,” Vaughan said. “Most come here from elsewhere in the region. They can get more for their money out here than in Loudoun or Fairfax.”

The cheaper cost of land in Prince William County makes developments such as Heritage Hunt economically feasible, said Bill Bullock, who sold houses in the community when it opened in 1997 and eventually moved in with his wife, Judy.

New houses in close-in communities often sell for $1 million or more, largely because land costs so much. At Heritage Hunt, single-family homes start at a third of that.

“We wanted to move into a new house, but not one that was 5,000 or 6,000 square feet,” said Bullock, 66, who sold a house in Vienna, where he had lived for two decades. “This enabled us to get in a new home that was properly sized for two people.”

Curt Dierdorff, 68, a retired human relations director for the Defense Department and now president of the homeowners board, said he and his wife sold their four-bedroom, 3,400-square-foot house in Fairfax County and bought a house in Heritage Hunt with 2,300 square feet. His wife’s only requirement was that they live close enough to Fairfax City so she can be a part of their two grandchildren’s lives.

“A lot of people just want to stay in the area because of family,” he said.

Marilyn and Frank Lamm sold their home on 40 acres in Lovettsville to move to Heritage Hunt. That places them roughly equidistant from their children in New Jersey, Ohio and North Carolina, and they had friends living in the development.

“If we would have had friends who live in Florida, we could have gone there,” said Frank Lamm, 80, a retired American Airlines pilot who flew international routes with his wife, a flight attendant with the airline.

“It seemed like there were a lot of people like us here,” said Marilyn Lamm. “It was like finding the right college campus.”

This being Washington, many of the residents have had impressive careers. So the regular residents’ night at the clubhouse, where people give casual talks to fellow homeowners, is not a meandering travelogue with slides. A member of the 9/11 Commission has discussed myths around the 2001 attack. A negotiator recalled talks he took part in to reduce nuclear weapons after the Cold War ended. A Smithsonian curator discoursed on a trip to Africa that he led. A university professor who has written books about George Washington offered an overview of the first president’s life.

Dierdorff said he never has regretted staying in the area instead of heading to the Sun Belt.

“A lot’s been written about people who move to Florida and they don’t know anybody,” he said. “Florida’s not all it’s cracked up to be.