2008: More momentous than you realized

December 4, 2009

2008 was quite a year for Philadelphia. There was, of course, the bestowing of the first national sports title in more than 20 years, but some equally exciting news was released earlier this week. After 50 years of losing population, the city's population has stabilized. In fact, it looks like we've even made modest gains. According to the US Census Bureau's updated population estimates for 2008, Philadelphia has 1,540,351 residents. The City challenged the Bureau's original estimate, which, at 1,447,395 was almost 93,000 lower than the revised one. Had the original estimate stood, it would have shown yet another population decrease.

Challenges have been allowed since 2001, and while successful challenges aren't terribly rare, few result in such a large increase in the revised estimate. In fact, the increase was larger even than the city anticipated. So what are these estimates and why do they matter?

Between the decennial censuses, the Bureau calculates population estimates. To do this, they start with a total number for the nation, just over 304 million for 2008, and apportion people to states and counties using a number of data including address information from tax returns, Medicare enrollment, birth and death records, and estimates from the American Community Survey on foreign-born population.  At the city level, they use the established county estimates along with data on housing unit changes such as building permits, demolitions, and new housing units...except in the case of Philadelphia, according to a helpful Census Bureau employee with whom I spoke.  The City and the County being one in the same means they calculate the estimate differently and do not include housing information. On an interesting side note, when they increase estimates for one geographic area, the Bureau must decrease estimates in other areas so the national total stays the same.

While population estimates don't determine voting district apportionments or major federal funding allocations - that is done using the decennial data - they do matter. Population estimates are used to determine federal funding allocations in some cases, as survey controls, and to monitor demographic changes.  Then there is the psychological value. Localities look to these numbers to get a sense of changes taking place in their communities. They are a sign, good or bad, of how a community is faring. 

The 1950 Census counted more than 2 million people living in Philadelphia. Since then, we've been shrinking, with our biggest losses occurring between 1970 and 1980, like many US cities.

The revised estimate for 2008 indicates that the city has gained population since 2000 - about 22,000 people. While these are estimates, even a skeptical reading of the numbers points to good news for the city as we await results of the more rigorous 2010 Census.  Philadelphia's decline may have lasted longer than some other cities, but it looks like the tide has finally turned.  Congratulations Philadelphia!

-- Jennifer Egmont, Project Manager