Forget Ozzie and Harriet. The married-with-children crowd no longer dominates the suburbs.

Nonfamily households — homes headed by a young, single professional or an elderly widow, for instance — now outnumber married couples with kids in the suburbs of the nation's largest metropolitan areas.

"It's incredible how things have changed since I moved up here. The traffic has tripled. Everywhere we look there are a lot of townhomes going up," said retiree Christine Reed, who moved to this Washington suburb nearly three years ago after her husband died.

The 2000 census findings fly in the face of notions of suburbs dominated by families similar to the one popularized in the 1950s sitcom Ozzie and Harriet — just Mom, Dad and the kids living under the same roof.

"This is a wave of the future," demographer William Frey said. "Suburbs are becoming much more diverse in terms of lifestyle."

The transition also poses challenges for officials in many fast-growing counties struggling to balance the needs of their oldest and newest residents.

"It's a tremendous drain on the available housing because we have different kinds of demands," said Jacqueline Byers, research director for the National Association of Counties.

Overall, the 2000 census showed suburbs continuing to attract all types of families, especially in the older, industrial urban centers of the Northeast and Midwest.

In the nation's 102 largest metropolitan areas, "nonfamilies" comprised 29 percent of households in 2000, up from 27 percent in 1990.

While the number of married-with-children homes grew, too, the share did not keep pace. It declined from 28 percent to 27 percent.

Married couples without children at home live in another 29 percent of suburban households. The remaining 15 percent are households such as single-parent homes.

Some of the demographic change came about because of divorce, a rise in single-parent homes, or because of the death of an elderly spouse, said Frey, an author of a Brookings Institution report that analyzed the metropolitan area data. Brookings is a Washington-based think tank.

Also, children of the giant baby boom generation have aged and most have left home, leaving "empty-nest" parents.

Meanwhile, young professionals have moved to escape high city rents or stay closer to jobs in sprawling suburban office parks.

Much of the change occurred over the last 15 years, with jobs at the heart of the transition, Byers said. In the Northeast and Midwest, singles and new families are not moving into older suburbs that had been quickly populated by baby boom families in the 1950s.

Consequently, more longtime elderly residents who did not move after their kids grew up were left behind.

"First people left, then retail followed them. Then ultimately the businesses and bankers of downtown began moving to the newer suburbs," said Robert Lang, director of the Alexandria, Va.-based Metropolitan Institute of Virginia Tech University.

The technology boom, meanwhile, spurred growth in the late 1980s and 1990s, as Internet start-ups and related firms sprouted in office parks outside commuter beltways.

That more youthful industry attracted fresh-from-school workers who favored suburban apartments and townhomes over longer commutes from the central city, Byers said.

"The singles moving to the suburbs are following the jobs," she said.

Chris Gonsalves says that's why his suburban Boston singles social groups gained popularity. Gonsalves, of Winchester, Mass., gave up his job in marketing to run the clubs full-time.

Many members work in a high-tech corridor northwest of Boston where cost-of-living expenses may be just as high as in the city, he said.

"In general, when people opt to live in the suburbs of Boston, it's not a financial choice," Gonsalves said. "It's a decision on commutes to work."

The suburban switch is most evident in the Northeast and Midwest, where many once-thriving suburbs of the 1950s have not remained economically competitive and cannot attract young singles, Lang said.