Geography Matters when Comparing Cities, Counties, and Metro Areas
Being from Alabama, and residing in neighboring Georgia, I keep up with headlines from my home town and home state. As an urban geographer who regularly accesses, analyzes, and visualizes census data as a component of my broader research and teaching, I was puzzled by the following headlines which appeared in one of the major Alabama news sources (AL.com) following the recent release of census estimates for cities and metropolitan areas:
- May 5: Alabama grows at edges: Huntsville, beaches buoy state, Census estimates show.
- June 4: Huntsville could become Alabama’s biggest city this year, Census estimates show.
- June 10: Huntsville jumps in latest Census count, on pace to be largest city in Alabama within two years.
- On June 13, a piece about metropolitan regions appeared: Which Alabama metro areas are growing, shrinking?
- These were then followed up with a July 4 rebuttal: Huntsville is never going to be Alabama’s largest metro.
While these are examples from Alabama, and there are certainly instances from other local and state media outlets elsewhere in the country, clearly with the recent release of Vintage 2020 population estimates from the US Census Bureau news headlines and articles have dramatized data about which cities may be growing or shrinking in particular states. However, such media articles often confuse readers regarding the broader perspectives most people have of cities compared to the larger metropolitan regions that contain them (although in several of the above cases the articles do include information further down in their narratives regarding the difference between city and metro area population change).
Cities and metropolitan areas are two different levels of geography. In many cases, a cluster of cities form a larger metropolitan region. Often, when many people think of or speak about a particular urban region, they may often do so by referring to the name of a metropolitan area’s largest core city. For instance, someone (including myself) may say “the traffic is bad in Atlanta.” But rather than referring to the city of Atlanta, with a little over 500,000 people in 2020, they are likely referring to the Atlanta metropolitan statistical area (MSA) with a population of over six million people. Likewise, someone from Hoover, a suburb of Birmingham, Alabama, may tell someone unfamiliar with the region that they are from Birmingham, referring to the larger metro region that may be more widely known.
Indeed, people go about their daily lives within metropolitan regions often transcending a variety of jurisdictions: cities, counties, congressional districts, zip codes, and a variety of other types of delineations. The US Office of Management and Budget delineates MSAs applied to U.S. Census Bureau data based on the concept of an MSA being comprised of a substantial core population nucleus along with adjacent counties having a high degree of social and economic integration, often via commuting patterns, with the core area.
Reading the headlines among local Alabama media regarding recent census estimates, an outsider unfamiliar with data and the urban geography of Alabama, and even some readers within the state, might conclude that Huntsville is about to become the largest urban center in the state. This is not true. Despite these headlines, Birmingham is still Alabama’s largest city. Moreover, what many people often think of as “Birmingham” — the Birmingham metropolitan region — is by far the largest MSA in Alabama and will remain so.
Graphs and maps visually reinforce the dynamic between city-level, county-level, and MSA-level data. Data presented in this article are from the U.S. Census Bureau’s Vintage 2020 estimates. These are not the actual data from the 2020 decennial census, which will be released over the coming months and year for more specific levels of geography. These are simply estimates that are part of the Census Bureau’s program designed to gauge the accuracy of the Census Bureau’s ability at estimating population totals related to the counts acquired from the decennial census. These estimates will be compared to the 2020 Census numbers that will be released later this year.
The graph below illustrates the top ten cities by total population in Alabama in 2020 and their population change each year from 2010. The top four cities at the top area of the graph include Birmingham, Huntsville, Montgomery, and Mobile. The sixth largest city, Hoover, is part of the Birmingham-Hoover MSA.
For further context, the following map illustrates the top twenty-five cities in Alabama by population in 2020 and shows their 2010 to 2020 percent population change. Seven of these cities are part of the Birmingham-Hoover MSA: Birmingham, Hoover, Vestavia Hills, Alabaster, Bessemer, Homewood, and Pelham.
County-level data also offer insight as a scale of geography in between individual cities and metropolitan statistical areas, which are comprised of one or more counties. The following two maps illustrate county population as a percent of Alabama’s total population in 2020 and population percent change from 2010 to 2020 by county, respectively. In the first map, we quickly see that it is no surprise that Jefferson, Mobile, Madison, Baldwin, and Montgomery Counties are the five counties comprises the largest share of Alabama’s population as these are the counties containing several of the state’s larger cities and are the core counties of several of the state’s MSAs. Shelby County also stands out as an area containing many of Birmingham’s “Over the Mountain” suburban cities.
In the second county map below, showing 2010 to 2020 population percent change by county, we see that the top five fastest growing counties are Baldwin (Daphne-Fairhope-Foley), Limestone (west of Madison County and part of Huntsville MSA), Lee (Auburn-Opelika), Shelby (part of Birmingham-Hoover MSA and contains many suburban cities), and Madison (Huntsville).
When visualizing metropolitan level data, the story regarding population change within urban regions in Alabama becomes more representative of the urban landscapes and experiences of metro area residents within the state. The following graph illustrates 2010 to 2020 population change in Alabama’s metropolitan statistical areas. Clearly, the Birmingham metro region is by far the largest urban area in the state and contains 22.2 percent of Alabama’s total population. The Birmingham-Hoover MSA is comprised of Bibb, Blount, Chilton, Jefferson, St. Clair, and Shelby Counties. Birmingham contains the state’s busiest airport (BHM), is where several rail and interstate highway routes converge, including Interstates 20, 22, 59, and 65, and including the I-459 bypass interstate highway. The Huntsville metro area contains 9.8 percent of the state’s population and is comprised of Limestone and Madison Counties. Huntsville is on Interstate 565, a spur of I-65.
Finally, the map below further illustrates the geography of 2010 to 2020 population and population change in Alabama’s metro areas, with the size of a point representing an MSA’s percent of Alabama’s total population and the color representing an MSA’s population percent change from 2010 to 2020.
To conclude, the U.S. Census Bureau regularly releases data sets for various levels of geography. We will be seeing data releases over the coming months for different levels of geography from the 2020 decennial census. As such, when media headlines allude to dramatic data points, take a moment to consider the different scales of geography that may be part of a more nuanced understanding of the story of population change in urban and metropolitan regions in a particular state.
