A combination of low-income people moving to the Lower Northeast from North Philadelphia, as well as impoverished immigrants coming to the area - mostly from Asia and Brazil - account for the precipitous rise in poverty in the Lower Northeast, said Matysik and others familiar with the area.
Need for food in local pantries has risen at such a high rate there, Matysik said, "we thought we'd missed some local economic event," such as the shuttering of a major factory.
"But it's immigrants moving in," he concluded.
An area once thought of as a white enclave is now 70 percent nonwhite, city figures show.
As a result, officials believe that the Lower Northeast is now the most ethnically and racially diverse area in the city.
Its communities include Frankford, Wissinoming, Oxford Circle, Crescentville, Lawndale, Burholme, Fox Chase, Rhawnhurst, Mayfair, and Tacony.
According to the ACS, the area with the highest poverty rate in the city between 2008 and 2012 (45 percent) included the neighborhoods of Nicetown, Tioga, Hunting Park, and Fairhill.
The lowest poverty rate in the city was 11 percent, in the Far Northeast.
Poverty in the Lower Northeast between 2008 and 2012 was 20 percent.
Overall, the city's 2013 poverty rate is 26.9 percent. That's the highest poverty rate of any U.S. city with a population of more than one million.
Population in the Lower Northeast is growing rapidly, mostly in Oxford Circle, which increased from 89,000 to 100,000 residents between 1990 and 2010, according to Ian Litwin, a city planner with the Philadelphia Planning Commission.
Litwin said the families moving in were larger than the families that once lived in the Lower Northeast. The average household size there was 2.56 people in 1990; in 2010, it was 2.92.
Hunger in the Lower Northeast is seen daily at the Feast of Justice food pantry at St. John's Lutheran Church in Mayfair.
The pantry saw a 30 percent increase in pounds of food distributed and a 52 percent increase in the number of people served between 2010 and 2013. Feast of Justice is the second-busiest pantry in the city, after Bridesburg United Methodist Church's pantry, Philabundance said.
"We're out here fighting," said Gary Furlong, 54, a seasonal landscaper who lives with his 75-year-old mother in Mayfair to consolidate resources. "I don't want to belittle myself, but we need the food pantry."
Average household income in the Lower Northeast fell 17 percent between the 2000 census and the 2008-12 ACS, from $59,017 to $49,170. The 2000 census measured conditions in 1999.
The largest drop in income, a 20 percent dip from $37,251 to $29,983, was recorded in the cluster of neighborhoods including Nicetown, Tioga, Hunting Park, and Fairhill.
Conversely, the greatest increase in average household income was recorded in Center City, where it went from $89,319 in 1999 to $103,564 in the period of 2008 through 2012.
The poverty rate in Center City went down 1 percent between the 2000 census and the ACS.
In Roxborough and Manayunk, poverty increased 42 percent in the same period. That's due in part to an influx of students from Philadelphia and Drexel Universities, said Eva Gladstein, executive director of the Mayor's Office of Community Empowerment and Opportunity.
The area also has a large population of low-income elderly, said Temple University sociologist Dave Elesh.
South Philadelphia showed the biggest drop in poverty - 13 percent.
That's attributed to gentrification in the area, which has seen middle-class people, many of them young families, moving into neighborhoods being rebuilt to accommodate a new cohort, according to David Bartelt, emeritus professor of geography and urban studies at Temple.
"New developments and restaurants have been spreading for the three years I've lived here," said Bob Kaufman, chairman of Temple's sociology department, who moved with his wife to Queen Village from Columbus, Ohio.
The changes look nice, but can't hide that fact that while the poverty rate in South Philadelphia is down, the poor there are still struggling, said Julie Zaebst, policy manager at the Greater Philadelphia Coalition Against Hunger. Zaebst lives in Point Breeze.
"In my neighborhood, there are lots of poor folks still just as poor as they've always been," Zaebst said. "Only now, they have better-off neighbors than they used to. The voices of long-term residents are being lost as more developers are looking to cash in on the money to be made in the neighborhood."