Drive west to east across Philadelphia on Poplar Street, and the range of income disparities is startling - from the caved-in porches and ramshackle rowhouses at 39th Street, to homes worthy of Architectural Digest, with touches like angled geometric windows and double-wide front doors, near Fourth Street.

Such is the magnetic force field of Center City's dynamism, where close-in neighborhoods have thrived as more distant ones are plagued by worsening blight.

And it is true not just of Philadelphia, but also of the eight-county region.

According to the Census Bureau's American Community Survey - which offers the first look since 2000 at the nation's smallest towns - pockets of wealth grew deeper in the furthest reaches of Chester, Gloucester and Burlington Counties, where farmland gave way to new, expensive houses.

But in the poorest parts of Delaware County, incomes have eroded since 2000, according to the survey, which aggregates five years of interviews, from 2005 to 2009.

In Chester City, which had the Pennsylvania suburbs' lowest median household income - $24,978 over the five years - purchasing power declined by 25 percent compared with a decade ago.

Households in Bridgeport, Montgomery County, also saw income drop by 25 percent, but median income was higher than Chester's, at $35,769.

Households in Hulmeville, Bucks County, took a hit, down 20 percent to $57,292, while Doylestown dipped slightly from $104,561 to $99,052.

In Philadelphia, neighborhoods contiguous to Center City, encompassing 20 percent of the city's population, showed dramatic income growth since 2000, but for eight of 10 city dwellers further from the hub, incomes fell or were at best flat.

Southwest Center City, including the south-of-South-Street area nicknamed "So-So," posted the largest income growth - up 61 percent for the five-year snapshot. Income was soundly up as well in Northern Liberties, Bella Vista, and Queen Village/Pennsport, while University City and Fairmount/Spring Garden also benefited.

But household income in Tioga/Nicetown in North Philadelphia showed the greatest decline - down 35 percent. Fairhill, in the rundown center of North Philadelphia, had the lowest average household income, $17,754. With 63 percent of its residents living in poverty, it is the city's poorest neighborhood.

For the city as a whole, median household income fell overall. Adjusted to 2009 dollars, it was $39,579 in 2000. In the 2005-09 survey, it was $36,669, for a decrease of about 7 percent.

Terry Bellamy, 42, a customer at Floyd & Diann's Tires & Wheels, 27th and Poplar Streets, is familiar with the city's extremes.

"Money's tight everywhere. But it's flowing better down that end," he said, pointing east toward the end of Poplar that plunges into Northern Liberties near the Standard Tap Room, a popular hangout.

Another tire shop customer, Vanessa Jackson, 59, lives in Northeast Philadelphia, off Cottman Avenue, where incomes at best have remained flat since 2000. She and Bellamy, her mechanic, had come a long way to get a good deal on badly needed tires, which Jackson said she could only afford because her son was paying.

Surviving on disability payments since 2004 because of severe carpal tunnel syndrome, Jackson, a former data-entry clerk, has watched her spending power erode. "I know a lot of people who lost cars" because of the bad economy, she said, "and a couple who lost houses."

The annual American Community Survey is designed to replace the "long form" of the once-a-decade census, to give the public and policy-makers a more current picture of the country.

Nationally, the survey found that the Washington metropolitan area was the nation's wealthiest over the 2005-09 period. Among the nation's poorest people were those living on Indian reservations.

On Tuesday, the population results from the 2010 census, will be released, as required by law, to allow for congressional reapportionment.