WASHINGTON (AP) — Rural America is losing population for the first time ever, largely because of waning interest among baby boomers in moving to far-flung locations for retirement and recreation, according to new census estimates.

Long weighed down by dwindling populations in farming and coal communities and the movement of young people to cities, rural counties are being hit by sputtering growth in retirement and recreation areas, once residential hot spots for baby boomers.

The new estimates, as of July 2012, show that would-be retirees are opting to stay put in urban areas near jobs. Recent weakness in the economy means some boomers have less savings than a decade ago to buy a vacation home in the countryside, which often becomes a full-time residence after retirement. Cities are also boosting urban living, a potential draw for boomers who may prefer to age closer to accessible health care.

About 46.2 million people, or 15 percent of the U.S. population, reside in rural counties, which spread across 72 percent of the nation's land area. From 2011 to 2012, those non-metro areas lost more than 40,000 people, a 0.1 percent drop. The Census Bureau reported a minuscule 0.01 percent loss from 2010 to 2011, but that was not considered statistically significant and could be adjusted later.

Rural areas, which include manufacturing and farming as well as scenic retirement spots, have seen substantial movement of residents to urban areas before. But the changes are now coinciding with sharp declines in U.S. birth rates and an aging population, resulting in a first-ever annual loss.

U.S. migration data show that older Americans are most inclined to live in rural counties until about age 74, before moving closer to more populated locations. The oldest of the nation's 76 million boomers turn 74 in 2020, meaning the window is closing for that group to help small towns grow.

"What baby boomers will do will be key to rural migration and growth," said Jason Henderson, a former vice president of the Federal Reserve Bank of Kansas City who is now associate dean of the Purdue University College of Agriculture. "Right now, we're just at the forefront of baby boomers entering retirement age, but many have been delaying retirement." Some will decide the time for moving back to the country has passed, he said.

Henderson expects a bit of a rebound for scenic retirement destinations as the economy improves, but nowhere close to the levels seen before the recession.

John Cromartie, a geographer at the Agriculture Department, calls the rural decline a potential turning point. "This period may simply be an interruption in suburbanization, or it could turn out to be the end of a major demographic regime that has transformed small towns and rural areas."

The scenic retirement destinations experiencing lower growth stretch wide, from the Upper Great Lakes and Appalachia in the eastern U.S. to the Sun Belt, the Missouri and Arkansas Ozarks and the Intermountain West. Boomer migration to many of these areas had typically yielded greater economic activity, including construction, landscaping and service-sector jobs that brought in workers of all age groups.

Signs of the recent bust are evident in places such as Fernley, Nev., a rural community in Lyon County, about 30 miles east of Reno. During the housing boom, Fernley prospered due to spillover residents from California's expensive Bay Area who were drawn to Fernley's affordable housing, temperate weather and lack of a state income tax.

By 2007, however, Fernley's growth began to wane amid recession and rising gasoline costs. Since then, Lyon County has posted one of the nation's worst population turnabouts: from 6.9 percent annual growth from 2000 to 2007, to a 0.7 percent annual loss between 2007 and 2012. The county now has a population of 51,000.

Retirees were "coming out of California, selling the house for a lot of money and coming up here and getting something nicer," said Fernley Mayor LeRoy Goodman, 71, citing his town's prime location near an interstate highway with easy driving access to Reno's casinos. "People can also walk out their back door and go hiking in the desert. The climate is pretty good; we don't have a lot of snow or rain."

But after the housing bubble burst, the retirees stopped coming. On Main Street, the Wigwam, one of the town's oldest restaurants, now does half the business it used to, according to Moe Royels, who opened the diner in 1961 and sold it five years ago.

"People moved out of town," Royels said from his seat at the restaurant, where he returns every afternoon for a cup of coffee. "Some of these subdivisions are still sitting vacant, with the curb and the gutter in but nothing else."

Due to changing baby boomer migration, rural retirement counties grew 0.4 percent annually from 2007-2012, down from 1.6 percent annually from 2000-2007. During the housing boom, these retirement destinations were growing faster than the rate of the nation as a whole but are now increasing more slowly. The overall U.S. population is now growing by about 0.8 percent each year.

In Florida, almost all counties experienced slower growth or a reversal of boomer population growth since 2010, said Mark Mather, an associate vice president for the Population Reference Bureau who analyzed the numbers.

Other counties showing sharp drop-offs in the boomer population include Forest County, Pa.; Trinity County, Texas; Middlesex County, Va.; and Banks County, Ga.

"The recent decline in migration rates among baby boomers is significant because boomers were expected to jump-start economic growth in rural America," said Mather, noting that parts of the rural Midwest and Appalachia had been losing population for decades. "But since the recession, we've seen more boomers aging in place. This is bad news because as baby boomers get older, they are less likely to move."

Other census findings:

—The 65-and-older population grew 4.3 percent between 2011 and 2012, to 43.1 million, or 13.7 percent of the U.S. population.

—Florida had the highest share of residents 65 and older, at 18.2 percent, followed by Maine and West Virginia. Alaska had the lowest share of older residents, at 8.5 percent, followed by Utah and Texas. By county, Florida's Sumter County was tops in the share of the 65-plus age group, at 49.3 percent.

—The 85-and-older population increased by about 3 percent from 2011 to 2012, to almost 5.9 million. The number of centenarians rose to almost 62,000.

—The nation's median age rose to 37.5, up from 37.3 in 2011.