At the same time, overall poverty in New Jersey - already reaching its highest rate in 50 years in 2011 - climbed even higher in 2012.
The survey, whose findings were released Thursday, shows that even with a drop in its poverty rate from 28.4 percent to 26.9 percent, Philadelphia remains the poorest of America's 10 largest cities, a position it has held for years.
The ACS estimated poverty and other characteristics for the entire United States by sampling 3.5 million addresses nationwide.
"The number of 26.9 percent Philadelphia poverty is tragic," said Eva Gladstein, executive director of the Mayor's Office of Community Empowerment and Opportunity. "This is 440,000 people or more - 135,000 of them children."
As it happens, the number of city children in poverty fell by three percentage points between 2011 and 2012, but with 36.8 percent of Philadelphia youngsters poor, that decrease didn't encourage anyone, said Kathy Fisher, an associate at Public Citizens for Children and Youth in Philadelphia.
The rise in the percentage of Philadelphia households needing food stamps - from 25.1 percent in 2011 to 26.3 percent in 2012 - comes at a time when federal lawmakers are considering major cuts to the program. Perhaps as early as Thursday, the U.S. House of Representatives will begin considering a plan to cut the nation's food-stamp program by $40 billion over 10 years.
As it is, food stamps (now called the Supplemental Nutrition Assistance Program, or SNAP) are already scheduled to be cut on Nov. 1 by $5 billion in fiscal 2014 alone.
The ACS report shows that median income in Philadelphia in 2012 ($35,386) was nearly identical to the figure in 2007, when the recession began.
"Poverty may have gone down, but wages haven't improved, which means we've got a long way to go," said Mariana Chilton, poverty expert with Drexel University's School of Public Health. "The business community needs to wake up and raise wages."
In most of the eight counties surrounding the city, the median income is at least twice that of Philadelphia.
The ACS also shows that New Jersey was one of just a handful of states in which the number of people in poverty increased between 2011 and 2012, from around 897,000 to around 934,000.
Earlier this month, Legal Services of New Jersey released a report that called 2011's poverty rate of 10.4 percent the highest since the 1960s. Now, the ACS report is saying conditions have worsened.
Some New Jersey experts blamed Superstorm Sandy, as well as high property taxes and low wages for the increase in poverty in 2012, although no one can say for certain.
In Pennsylvania, where the poverty rate remained virtually the same in 2012 (13.7 percent) as it did in 2011 (13.8 percent), nearly 1.7 million people stayed mired in poverty.
Throughout the United States, overall poverty remained practically the same in 2011 as it was in 2012, with 15 percent of Americans living below the federal poverty level of $23,050 for a family of four.
The story in Philadelphia's suburbs was mixed.
The poverty rate in Delaware County in 2011 was 9.9%. In 2012, it was 11.8%, registering the highest increase in any of the eight counties in the Philadelphia area.
While the median income remained practically identical in 2011 and 2012 (around $61,000), the percentage of households needing food stamps in Delaware County increased from 9.9% to 11.1%.
County officials could not explain the increase. But Joanne Castagna, director of the Loaves and Fishes Food Pantry in Prospect Park, said need in the county was palpable.
"We've seen so many people lose their houses, then move into apartments they can't afford," she said. "We can't keep up with the demand. People coming here have virtually nothing to eat."
As in Philadelphia, poverty went down in Camden and Bucks counties. The five other regional counties saw increases.
In New Jersey, "if you look at flat wages, under-employment and the increasing cost of things, it doesn't take much to push people over the edge into poverty," said Adele LaTourette, director of the New Jersey Anti-Hunger Coalition.
The ACS also looks at poverty from 2000 to 2012.
The number of Pennsylvanians living in deep poverty - 50 percent or below the federal poverty line - rose from more than 482,000 in 2000 to more than 745,000 in 2012, a change of 1.9 percent. In New Jersey, deep poverty went up 1.1 percent.
Advocates contend that deep poverty was created by the federal government's cuts in the welfare program.
Similar worry pulsates this week, with the House poised to cut SNAP.
"It's a disaster coming down the pike," Chilton said. "With so much poverty, the House is proposing to put a knife in an already open wound."
Contact Alfred Lubrano at 215-854-4969 or firstname.lastname@example.org