The previous post described how the changes to the metropolitan area definition resulted in the splitting of numbers of large Metropolitan Statistical Areas (MSAs) as they were delineated for the 2000 census into 2 or more MSAs in 2003. This raised the obvious question, what was it about the new definition that produced these changes? The answer proved to be complex and bizarre, and the situation was only made worse by a horrible decision made by the Census Bureau with the 2010 Urbanized Area (UA) definition.
A major change made in the MSA definition first used in 2003 was to begin the delineation with the Urbanized Areas, including all counties with substantial portions of a UA in the MSA. After that, commuting to those central counties was used to add outlying counties to the MSA. The definition included provisions for merging adjacent MSAs using the same commuting criterion, but this made it highly unlikely that adjacent large MSAs could ever be merged. So as a result, the general extent of MSAs was determined by the extent of the UAs. If an area of contiguous urban settlement were split into 2 or more UAs, this would likely produce multiple MSAs.
So now we have to go to the UA definition. The new UA definition for the 2000 census provided for the splitting of large urban agglomerations into multiple UAs using the MSA (and CMSA and PMSA) boundaries as delineated for the census. So the extent of the MSAs depended on the UAs, and the extent of the UAs depended on the MSAs! It is a circular definition!
So what happens with the UAs for 2010? The Census proposed to maintain the status quo, keep the largest UAs with populations over a million the same, but not split smaller urban agglomerations, so contiguous UAs would be merged. This generated opposition from those in areas that would be merged, as this could affect the receipt of federal funding. The. Census response was to surrender and make the decision that the set of UAs that were delineated in 2000 would be frozen! Each 2000 UA would continue to be a UA in 2010! And since the MSAs continued to be based on the UAs, they would be largely frozen as well.
Since the beginning of the UA and MSA definitions in the mid-twentieth century, the areas had been allowed to evolve, with areas being combined as formerly separate areas grew together and were more reasonably considered a single entity. For example, Dallas and Fort Worth started as separate UAs and MSAs but for decades have been considered to be a combined area. What the Census Bureau did with the 2010 UA definition was to say that the delineation of urban and metropolitan America would be frozen as it was in 2000 and would not be allowed to further evolve. This was a truly horrible decision. And the Census Bureau knew it, as was clear from the misleading obfuscation of what they were doing in the Federal Register notice for the 2010 UA definition.