The effect of the changed definition of Metropolitan Statistical Areas

In an earlier post I explained why I chose to use the larger Combined Statistical Areas (CSAs) for my urban patterns research rather than the more common and familiar Metropolitan Statistical Areas (MSAs). I felt that in some cases the MSAs did not encompass what I felt was the whole metropolitan area. Exhibit 1 was the New York MSA, which did not include any of the Connecticut suburbs.

Before this, I had no occasion to systematically look at the extent of all of the large MSAs. But my recollection was that the MSAs were not always this limited. For example, the New York MSA used to include areas in Connecticut, and Raleigh and Durham had been a single MSA. I decided to start digging to find what had happened. It turns out that the Office of Management and Budget (OMB) made major changes to the MSA definition in 2000, which was first used to delineate new MSAs in 2003. This is also when the CSAs were introduced.

I decided to do a systematic comparison of the last MSAs delineated under the old definition, which were used in reporting the 2000 census, and the areas delineated in 2003 using the new standards. I looked at the 49 MSAs (and CMSAs, which were nothing more or less than MSAs for which subdivisions had been delineated) with populations over a million in the 2000 census. For a majority of the 2000 MSAs, the 2003 MSAs produced with the new definition were similar, varying only in the outlying counties included. But 18 of the 2000 MSAs were split into 2 or more MSAs in 2003, in one instance, into 6 different MSAs. These included New York and Raleigh-Durham.

For those areas where CSAs had been delineated in 2003, I compared their extent to the 2000 MSAs. In nearly all cases, the CSAs were quite comparable to the 2000 MSAs. They included the multiple new MSAs produced by the splitting of the older areas. No wonder I found the CSAs more reasonable than the MSAs. OMB thought those larger areas better represented the extent of metropolitan areas up through 2000!

A research note providing the complete results of these comparisons is posted on the Research page and can also be downloaded here.


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