While the civically obsessed await the results from the off-year election going on, here is a question for later in the week. Is the city of Pittsburgh growing?
Scheduled to be released this week is the latest annual data point for population in the city of Pittsburgh as of July 2014. Last December 2014 population estimates for the nation and individual states were released. In March the comparable 2014 data for individual counties and metropolitan areas came out. What will come out this week completes the data trifecata for the year with population estimates for individual municipalities to include the city of Pittsburgh.
Whether the city of Pittsburgh is growing is a matter of moderate public debate and I assure you everyone has some very strong ideas on whether the population trends in the city are positive or negative, and as often as not debate with references to regional, county and city population trends conflated to the point of confusion. But looking to the future this is an important thing with a mayoral goal I hear about of growing the city by 20,000 over a coming decade, though the starting point for that calculation seems to keep slipping. Population growth has also been at least implicitly part of the debate over what impact things like the Pittsburgh Promise can have on the city of Pittsburgh.
What do we think we know? For sure the city of Pittsburgh has been declining in population since the 1930s. Some say since the 40s or 50s, but population growth recorded between 1930 and 1940 is really the result of some annexations that expanded the geography of the city of Pittsburgh. Account for that and the actual population in the city of Pittsburgh proper was already pushing downward back then. Yet a few years ago the buzz was about the first recorded population increase for the city of Pittsburgh in many many decades
when estimates for 2011 showed population increase between 2010 and 2011.
To oversimplify a complicated subject, these annual population estimates become ever more problematic the smaller the scale of geography. So municipal level population estimates have issues that are not so bad at county, MSA or state levels. A case in point is the population increase first observed for the city of Pittsburgh between 2010 and 2011 per the news in the previous link. You may read my contemporaneous moderation in talking about the growth estimated at +1,780 that year. It just did not seem right and I knew the numbers would not hold up.
Indeed in revisions the very next year, the population growth over that same period was re-estimated to be only +392, or 77% smaller than originally reported. A much smaller, but still positive, change, and for the city of Pittsburgh even population stabilization is a pretty big story. The revision I can explain in multiple ways having to do with data revisions to some college dormitories numbers in the city and also due to some temporary methodology changes
the Census folks used that year, but soon abandoned.
For the city of Pittsburgh the data picture gets more conflicted actually. The primary data input for population estimates for individual municipalities is the population change for the counties where they rest. The previous year's data on population change (between 2012 an 2013), Allegheny County was estimated to have increased
by +2,579 , but the city of Pittsburgh was estimated to have returned to decline of 348 This year, we already know the estimated population change between 2013-2014 for Allegheny county is actually a decline
of 1,698, so the estimated change for the city of Pittsburgh is going to be negative, the question is really just by how much. We can debate ad nauseam how close the estimated get to ground truth.
There is a side story to all of this of note. As mentioned here in the past, the main input to the municipal level breakdown of population change within a county is the pattern of building permits issued by municipality. One odd thing discussed here in the past is that the data the city of Pittsburgh itself reports on the number of building permits
in any multiple unit structures between 2005 and 2013. Since it seems pretty obvious there were building permits issued for new multiple unit structures, you have to wonder if the population estimates that resulted were biased downward in some way. The census methodology is only as good as the data it uses, and the building permits data is self reported by municipalitie
s so if true the city only has itself to blame in some way. It looks like that might have just changed with the latest building permits data for the city reporting a new 215-unit building permit issued in December 2014. Then there is an even more complicated subject o
ver whether housing unit conversions are property recorded in the data for the city.
I won't even begin to go into natural population trends impacting the city of Pittsburgh
Yes, I could go on.. but enough yes?