WASHINGTON, D.C. — America's small cities are losing some of their traditional appeal to upwardly mobile families seeking wholesome neighborhoods, a stable economy and affordable living.

A review of newly released census data shows, for example, that cities of between 20,000 and 50,000 residents have lagged behind their larger counterparts in attracting higher-educated residents in this decade.

In 2000, small cities, which include remote towns and the distant suburbs known as "exurbs," ranked at the top in the share of people with college diplomas. They slipped to No. 2 last year with 30 percent holding degrees — in between medium-sized cities, which had 31 percent, and big cities, at 29.8 percent.

Poverty is growing in the small cities, fueled partly by population growth, although average median income of $60,294 in those communities is still higher than other places.

Small cities looking more and more like bigger cities over the decade ranged from places like Hobart, Ind., and Mount Pleasant, Mich., to Anniston, Ala., and Greenville, Miss. Compared with previous years, they had smaller incomes, higher housing costs, longer commutes, more poverty and more single-parent families.

Demographers attributed some of the shifts to the housing downturn and a spike in gasoline prices, which has hit residents in the far-flung exurbs harder. Many families in smaller towns also are looking for jobs in larger cities because of the current recession and are rethinking the wisdom of a lengthy commute to work.

Some small cities may have become victims of their own success. As their local economies boomed mid-decade, many places grew rapidly and attracted lower-income residents needed to build roads, schools and other public works projects. Some of these areas have shot up in size and are now medium-sized communities.

"Small towns have a certain appeal to people, and their quality of life there is backed up by the data," said Mark Mather, associate vice president of the nonprofit Population Reference Bureau. "But as more people move in, small towns start to lose the qualities that attracted people there in the first place."

The shifts are notable in the ranks of the educated.

According to census data, smaller cities in California, Texas, Florida, Michigan and New York had declines in the share of residents with bachelor's degrees, ranking among the lowest in the nation. They included Bell, Calif.; San Benito, Texas; Jasmine Estates, Fla.; Hamtramck, Mich.; and Newburgh, N.Y.

North Potomac, Md., posted some of the highest shares of college graduates in the nation. Still, its share fell in the last decade, from 75 percent in 2000 to 70 percent. Other highly educated towns that saw brain drains were East Lansing, Mich., North Druid Hills, Ga., and Greenbelt, Md.

The findings come as President Barack Obama has pledged to upgrade mass transit and other urban priorities in inner cities and their close-in suburbs. That could create additional shifts in residential patterns to larger-populated areas, especially for younger couples and small families who more readily move.

The AP review found both extreme poverty and wealth in smaller-sized cities.

For example:

— Poverty has risen in small cities, from 10.8 percent in 2000 to 12 percent. In big cities, poverty declined slightly, from 17.7 percent to 17.6 percent.

— Homeownership costs in small cities are growing less rapidly, partly a reflection of the housing collapse in many exurbs. In 2000, big cities trailed small cities when it came to the share of residents with monthly costs of more than $1,000 — 56 percent to 61 percent. By 2008, 82 percent of big-city residents were paying the high costs, compared with 78 percent for small cities.

— Carbondale, Ill., had the lowest median income, at $17,508, followed by small cities in New York, Louisiana, Alabama and Ohio. Darien, Conn., topped all other cities with the highest median income, at $188,823.

"There are lots of small towns and rural areas that are struggling," Mather said. "Many were struggling before the current recession, so it might take more than a dose of stimulus funds to put them on the road to recovery."

The data, from the American Community Survey, represent three-year averages covering 2006 through 2008, providing a snapshot of every community with at least 20,000 residents. Medium cities are defined as having 50,001 to 150,000 residents, and big cities have more than 150,000.