Wednesday, November 14, 2012

Cities are Growing but Sprawl Continues

by Dan McCue
Research Manager
The 2010 decennial Census provided new data to look at urban growth patterns over the past decade, enabling us to update our views on the latest trends in suburban sprawl and movement ‘back to the cities’.  Growth in our nation’s largest cities has been of particular interest not just because these areas are home to so many people, but because they are the engines of economic growth that often serve as bellwethers of the overall economic health of a region or even the nation as a whole. As has been reported elsewhere, growth in cities has been positive over the past decade, with the majority of the core cities in the nation’s largest metropolitan areas experiencing household growth.  Indeed, our analysis has found that core cities in 72 of the 100 largest metro areas grew in the 2000s. But at the same time, and in contrast to many headlines, our research also shows that the pace of growth in suburbs and exurbs exceeded that in the central cities in all but five metros. Suburban sprawl was alive and well.

Tracking Urban Growth:  Data and Methodology

Using 2000 and 2010 Census data for the top 100 metros, we analyzed the spatial distribution of household growth over the last decade by looking at changes in core urban cities (defined as large cities with populations over 100,000), suburbs (defined as urbanized parts of metros not in large cities), and exurbs (defined as all remaining non-urban tracts).

Our analysis found that, while household growth in core urban cities did occur, on the whole it was slower and smaller than growth in the suburbs and exurbs (See Figure 1).  Overall, the rate of household growth in the core urban cities of these 100 metros was just 6.4 percent, which was much slower than that of suburbs (10.5 percent), and a fraction of the growth rate of the exurban areas (28.3 percent).  In terms of magnitude, the number of households in the top 100 core urban cities grew by just 1.65 million in 2000-2010 while during the same period suburbs increased by 3.0 million households and exurbs grew by 3.2 million.

Source: JCHS Tabulations of U.S. Census Bureau data

Failure to grow as fast or as much as the suburbs and exurbs over the past decade caused the share of households living in the top 100 metropolitan areas’ core urban cities to drop.  Core urban cities were home to fully 39 percent of all households in 2000, but accounted for only 21 percent of all metropolitan area household growth.  Exurban areas, on the other hand, represented only 17 percent of all metropolitan households in 2000 but 41 percent of total metropolitan household growth in 2000-2010. As a result, the share of households living in urban cities dropped from 39 percent in 2000 to 37 percent in 2010, while the exurban share increased from 17 to 20 percent.  The suburban share remained stable at 43 percent of all households.

Looking individually at the distribution of growth within each of the top 100 metros, we found that even in metros where core urban city household growth rates were high, suburban and exurban growth rates were often higher (click here for Excel spreadsheet).  And in the five metros where core urban cities grew faster than the metropolitan areas as a whole, core city growth rates were only 0.5 percentage point higher than overall metropolitan growth rates.  In contrast, in the remaining majority of metros, core urban growth rates were fully 8.8 percentage points slower than the overall metropolitan growth rates.  As a result, many metros saw their share of households living in core urban cities drop significantly (See Figure 2).

Notes: Data include the 100 largest metro areas, ranked by population in 2010. Cores are cities with populations over 100,000. Suburbs are all urbanized areas outside of cores. Exurbs are the remainder of the metro area. Census data do not include post-enumeration adjustments.  Source: JCHS tabulations of US Census Bureau, Decennial Census.

To summarize our top-level findings, data from Census 2010 gives evidence of a ‘back to the cities’ movement in the form of household growth occurring in the majority of core urban cities of the top 100 metropolitan areas.  However, our analyses so far have also provided much more convincing evidence that suburbs and exurbs continued to drive metropolitan household growth over the past 10 years.  Indeed, even in the fastest growing cities, growth typically was neither as fast nor as large as that occurring in the surrounding suburbs and exurbs.

1 comment:

  1. The information is interesting, but I don't think what is presented is sufficient to conclude that "sprawl continues" (quoting the headline). To draw that conclusion, one would need to 1) concluded have concluded that any growth in the number of households outside of the core urban cities is, by definition, contributing to "sprawl." Even accepting that growth in number of households is the appropriate metric (as opposed to development of housing units, which is probably more appropriate), I believe that this approach is a narrow view of the topic.

    In my view, sprawl has more to do with the characteristics of development than it does with the location of that development (though both are important).

    In particular, it is crucial to know the density and smaller-scale locational characteristics of the new development. If the new development is low-density, mostly single-use, and mostly dependent on automobile travel, then the "sprawl continues" conclusion may be warranted.

    If, however, the new development is higher density, includes a mix of uses, and has access to some reasonable version of transit usable for daily trips, then it may not be "sprawl" continuing, but instead the core urban area extending (whether within or outside of the core urban city jurisdiction). Core urban areas extending, in terms of development density, cannot be considered as sprawl -- otherwise, development that has led to expansion of city limits would need to be considered sprawl until annexation occurred.

    So -- bottom line -- if Figure 1 had a couple of lines that showed density of development, and that those lines were able to show that, in the suburban and ex-urban areas, low-density development was continuing (defined as lower, at minimum, than the lowest-density development that currently exists in core urban cities), then I'd sign on to the notion that "sprawl continues." Otherwise, it's a case of "More data/information is needed to determine whether the lower overall quantity of household growth in core urban cities, as compared to suburban and ex-urban areas, constitutes an expansion of sprawl, or an expansion of cities....or a bit of both."