Excellent article from New Geography.
Since 2014, the City Sector Model has been used to portray population trends by functional area within the 53 major metropolitan areas (major metropolitan areas). The current edition classifies small areas (zip code tabulation areas) by demographic factors into five categories (Figure 1). The first two are urban core (central business district and inner ring), while the last three are suburban or exurban. The suburban areas are largely within the continuous built-up urban areas, while the exurban areas are generally in the metropolitan areas, but outside the built-up urban areas.
The advantage of this type of analysis permits much finer grained analysis of the urban form, principally splitting between areas similar to pre-World War II urbanization (urban core) and principally suburban (and exurban) areas that have developed since the war. The urban cores are denser and have lower levels of automobile use. The suburban and exurban areas are less dense and more automobile oriented.
Previous urban core versus suburban and exurban analysis relied principally on municipal boundaries, and assumed the urban core to be defined by one or more central municipalities. However, such analysis classifies large suburban areas, such as most of New York City’s Staten Island as urban core, while classifying large, dense, transit oriented areas adjacent to the city of New York, especially in New Jersey, and inner suburbs of Boston as suburban. Some central cities, such as Phoenix and San Jose are nearly all suburban in form.
This article describes expansion of the City Sector Model to include the 52 additional middle-sized metropolitan areas, those with from 500,000 to 1,000,000 population in 2014 (the middle year of the 2012-2016 small area data used).
Middle-Sized and Major Metropolitan Areas
As previously reported, the 53 largest metropolitan areas had 14.5 percent of their population in the urban cores, according to data from the American Community Survey for 2012-2016 (See Note). 85.5 percent of major metropolitan area residents lived in suburban and exurban areas.
The middle-sized metropolitan areas are even more dispersed, with considerably lower urban core population shares than the major metropolitan areas. In 2012-2016, the middle-sized metropolitan areas had 4.1 percent of their population in urban cores, less than one-third that of the major metropolitan areas, leaving them 95.9 percent suburban and exurban. Among the non-urban core classifications, the largest contrast was in the exurban areas, where 28.1 percent of the middle-sized metropolitan area residents lived, about three-quarters above the 16.4 percent share for the major metropolitan areas (Figure 2).
The population growth rates by sector were similar in the two categories of MSAs between 2010 and 2012-2016. Among the major metropolitan areas, the newer suburbs had the strongest annual growth rate. The exurban growth rate was the second strongest, followed closely by the Urban Core: Central Business District (Figure 3) although this sector has by far the smallest share of the population.
Similarly, the newer suburbs had the strongest growth rate in the middle-sized metropolitan areas, while the exurbs grew second fastest. Both urban core sectors dropped in population. (Figure 4)
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