In contrast, from 1970 to 2010, "the share of those in lower-income households increased from 30 percent to 47 percent, and the upper-income group went from 11 to 10 percent - meaning Philadelphia got poorer," the report says.
A sturdy middle class is widely deemed important for a city's economic health and social stability.
Although the reasons why the middle class declined were not the focus of the report, Eichel said part of the decline, especially from 1970 to 1990, is attributable to people moving to the suburbs because of schools, jobs or the lifestyle there.
The decline of manufacturing jobs in the city was definitely a factor, he said. The drop can also be attributed to people in the middle class dying and not being replaced, he said.
Although the Philadelphia Research Initiative does not back any specific policy recommendations, Eichel noted that there are certain items found to appeal to middle-class residents. They are:
* The city's 10-year tax abatement on housing construction and renovation.
* The growth of charter schools.
* The development of amenities like bike lanes and dog parks.
Another way to grow the middle class would be to enhance workforce opportunities for lower-income residents, he said.
Among the report's findings:
* In 1970, 81 percent of the city's census tracts had middle-class majorities, including much of South and West Philly, the Northeast, and large parts of North Philly, including Olney and Logan.
* In comparison, the Census Bureau's 2007-11 American Community Survey shows that only 31 percent of the city's census tracts were majority middle class.
* In 1970, 44 percent of the city's middle class did not have a high-school degree. In 2010, "only 8 percent were able to make it [to middle-class status] without a high-school diploma," said Susan Warner, the report's author.
* The city's middle class has become more racially diverse.
* With the decline in manufacturing jobs, a greater percentage of middle-class people are now working in finance and other business and professional services.
The report, for the most part, defines middle class as households with incomes between 67 and 200 percent of regional median household income. For 2010, that meant households with income from $41,258 to $123,157.
For the census-tract data, middle class was based on family income. For 2010, that meant incomes from $51,974 to $155,147.
The report, " Philadelphia's Changing Middle Class," can be found at pewtrusts.org.
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