And that is just the issue of understanding the difference between the "City of" Pittsburgh and nearby municipalities. The broader "Pittsburgh" is the Pittsburgh region, sometimes talked about in terms of a common defintion used as the Pittsburgh Metropolitan Statistical Area (MSA), which currently 7 counties in Southwestern Pennsylvania. There are other definitions such as the commonly referred to 10 county Southewestern Pennsylvania region (the MSA plus Greene, Indiana and Lawrence counties) which is used by both the Allegheny Conference and the Southwestern Pennsylvania Commission. Then there is a 19 county "Pittsburgh Economic Area" used by the Bureau of Economic Analysis. The late John Craig focused the Pittsburgh Indicators project on a 22 county region stretching into WV and OH. Looking further there are newer and more notional things such as the 32 county "Power of 32" region that extends far into Ohio and West Virginia and has a toehold into Maryland, or the amorphous "Cleveburgh" which clearly exists, yet doesn't in any official or quasi-official way.
In 2003 a major revision of metropolitan area definitions resulted in Armstrong County being added to the Pittsburgh Metropolitan Statistical Area. It was also the revision that added the term "Micropolitan Statistical Area" to the lexicon of regional thought. Two nearby micropolitan areas were defined. One is the New Castle micropolitan statistical area comprised of Lawrence County and the other is the Indiana County micropolitan statistical area. To futher confuse the issue there was a new type of region called the Combined Statistical Area (CSA) created at the time and Lawrence County is joined with Pittsburgh to form the Pittsburgh - New Castle CSA while the Indiana County micropolitan area remains on its own. Confused yet ? We're just beginning.
Why does it matter?
In lots of ways it does not and folks will define Pittsburgh any way they choose. There is an argument that corporate site selection folks will not even consider an area if it s not part of a metropolitan statistical area. How true that really is at the end of the day I am not sure anyone really knows. The official metropolitan area defintions matter at the end of the day at least to the hospitals since it really will impact what medicare rates they get to charge if they are not included in the definition of any metro area. Thus in the last change that impacted Pittsburgh the addition of Armstrong County was a big deal for the health care providers in Armstrong County for sure.
Over time the Pittsburgh Metropolitan Statistical Area has changed. Old timers will sometimes ask me the current definition of the Pittsburgh Standard Metropolitan Statistical Area (SMSA), which is actually much an oxymoron since SMSA is not a defintion that has been in use for decades. Currently unused terms include Primary Metropoltian Statistical Areas (PMSA) and Consolidated Metropolitan Statistical Areas (CMSAs). For a period of time there were two local PMSA's: Beaver County was its own PMSA and the Pittsburgh PMSA was 4 other counties. The Pittsburgh-Beaver County Combined Metropolitan Statistical Area was the region most talked about. Got all that? If not, don't worry too much as those definitions at least are all now anachronisitc.
On a side note. It is remarkable that Butler County was not part of the official definition of the Pittsburgh metropolitan area definition until the 1990's. There just were not enough people commuting between Butler county and nearby counties to justify including it in the official definition of the MSA. Think about that? Now virtually all Butler County municipalities bordering Allegheny have a literal majority of their resident workers commuting into Allegheny County.
OK.. if you are still reading, the more interesting question is what will the next change be to any of these definitions? What county will be added to the official definition of the Pittsburgh MSA next?
The guidelines on metropoltian area defintion has had a major change in the recent notice and the one a decade ago in that there is no longer any role for local opinion on what. There is no 'lobbying' that matters any longer. Local perceptions once actually did get factored in and local opinion of what area defined a metropolitan area could be included in the official definitions promulgated by OMB. Today it all depends on data, specifically commuting data. If enough residents in a county commute to jobs located in counties that make up a metropolitan or micropolitan area, then it is included in the definition of the area.
The threshold for whether a county gets included in a metro area all comes down to a focused and unique metric called the employment interchange measure. The employment interchange measure for two regions is basically the proportion of resident workers in a smaller region who work at jobs in the larger region plus the proportion of resident workers in the larger region that work in the smaller. Say that 3 times fast. If a smaller adjacent region has an employment interchange metric higher than 0.25 it gets inlcuded in the larger area. I'll skip the numbers for Greene and Indiana counties which are not that close to being included in the Pittsburgh metropolitan statistical area yet, but Lawrence County is really worth checking.
So in 2000 I get this commuting data for Lawrence County into any fo the 7 counties of what is now the Pittsburgh MSA:
|Residents of Lawrence County Working in|
|Resident workers in Lawrence County||37,529|
The latest data available on county to county migration flows from the 2006-2008 American Survey gives me this:
|Residents of Lawrence County Working in:|
|Resident workers in Lawrence County||37,083|
So 8,059/37,083= 21.3%
Note in both years the proportion of folks in the 7 counties commuting to work in Lawrence county is pretty negligible.. a fraction of a percent, so I have not included those numbers here even though they do matter in the full calculation of the employment interchange measure.
So that 2006-2008 data is not enough for Lawrence County's inclusion in the MSA.. but that data goes back a few years. The next round of redefinitions of Metropolitan Statistical Areas will come in 2013 and based on more recent data including data from the 2010 Census. So if the trend from 2000 to the 2006-2008 period were extrapolated a few years, Lawrence County would get closer to that .25 threshold, but would not quite make it yet.
But... I bet the recession has had impacts on employment and commuting trends. It may be that there has been an acceleration in employment concentrated in Allegheny County in just the last few years. So I still think it is possible for Lawrence to be added this upcoming cycle. If it does not happen, it will be awfully close.
So we will have to wait to see if it becomes an 8-county Pittsburgh Metropolitan Statistical Area and with it a gey ographthat stretches closer toward that Cleveburgh future. There could be 2nd order effects of this with potential future impacts on the defintion of the Youngstown MSA.
One last thing. A big change recently in the ephemera of metropolitan area defintions is the frequency at which metropolitan statistical areas will be redefined in the future. Until now there were regular updates over the decade to metropolitan area definitions as new commuting data came out. The new guidelines are that the changes to area definitions will only happen every decade. So if Lawrence County just misses inclusion in the MSA by a very small amount this cycle... then even if commuting patterns continue to change the definition of the MSA will not be altered again until some time after 2020.