The City-States of America

We do not really think much about city-states anymore. With the exceptions of such places as Singapore and Hong Kong, the term “city-state” often conjures up the image of Athens or Sparta.

However, through a bit of number-crunching of data from the United States Census, I have found a new way to think of city-states when it comes the United States: those states where the majority of their populations lie within a single metropolitan area. For example, the state of Illinois is a city-state because, despite its large physical area, two-thirds of its population lies within the counties that make up the Chicago metropolitan area.

With that, I present The City-States of America:

downloadable as a high-resolution PDF

These are the fourteen states (plus the District of Columbia) where over the half the population of that individual state lies within a single metropolitan area (the state-by-state population fractions in largest metropolitan area at the end of the post). And there’s not much of a pattern to this. For example, New York, Massachusetts and Rhode Island all grew out of single large population centers that were colonized early on, and this might appear to be a reason for being a city-state. However, Georgia does not have a similar history and is a city-state. On the other hand, Utah was also primarily colonized in a single city, yet is not a city-state.

More generally, these city-states don’t fit a single category in my mind: they are on both coasts as well as being landlocked, and encompass the non-contiguous states of Alaska and Hawaii.

However, there may be a great explanation for the distribution of city-states. Please put any theories for what is going on in the comments.

Scientific Background

This concept, The City-States of America, is similar to that of the primate city, a term coined by Mark Jefferson in 1939. A primate city refers to a city that is disproportionately larger than the other cities in that country or region. This idea is related to the Zipf distribution, a scale-free or power law distribution that often describes the ranks of the city sizes within a single country. In these distributions there many small cities dominated by a small number of extremely large cities, whose sizes are described by the exponent of the fit of the power law.

An explanation for how such an even distribution can occur is that of Gibrat’s Law, which posits the idea of proportionate growth — larger cities grow proportionally faster — can lead to this long tail of city sizes. A recent scientific paper that explores cities and Gibrat’s law is found here.

How Did I Make This?

I downloaded the United States Census data for the metropolitan and micropolitan statistical areas (MSA’s), using the 2009 estimated values. I calculated the populations for each of these areas within each state by county. For example, the New York City metropolitan area spans multiple states. I included a separate NYC MSA in each of these states, with populations made up of only those counties within the state. So the Connecticut NYC MSA only included Connecticut counties in the calculation of the population of that MSA.

Examining the largest MSA population for each state, I then compared that to the estimated population of the entire state, also as of 2009. Those states that had over 50% of their populations within a single MSA were classified as city-states.

State-by-State Population Fractions

Below are the percentages of the state populations (plus DC) that live within the largest metropolitan statistical areas, in decreasing order:

  1. District of Columbia: 100%
  2. Rhode Island: 100%
  3. New Jersey: 73.3%
  4. Nevada: 72.0%
  5. Hawaii: 70.1%
  6. Illinois: 67.5%
  7. Arizona: 66.2%
  8. New York: 64.6%
  9. Massachusetts: 63.2%
  10. Delaware: 60.4%
  11. Minnesota: 59.7%
  12. Georgia: 55.7%
  13. Alaska: 53.6%
  14. Washington: 51.1%
  15. Colorado: 50.8%
  16. Maryland: 47.2%
  17. Oregon: 47.0%
  18. Michigan: 44.2%
  19. New Mexico: 42.7%
  20. Utah: 40.6%
  21. Nebraska: 40.6%
  22. Idaho: 39.2%
  23. Maine: 39.2%
  24. Missouri: 35.6%
  25. California: 34.8%
  26. Connecticut: 34.0%
  27. Vermont: 33.5%
  28. Oklahoma: 33.3%
  29. Virginia: 32.5%
  30. New Hampshire: 31.9%
  31. Pennsylvania: 31.8%
  32. Florida: 29.9%
  33. Kansas: 29.8%
  34. South Dakota: 29.3%
  35. Wisconsin: 27.6%
  36. Indiana: 27.1%
  37. Louisiana: 26.5%
  38. Texas: 26.0%
  39. Tennessee: 25.1%
  40. Alabama: 24.0%
  41. Arkansas: 23.7%
  42. Kentucky: 23.4%
  43. North Dakota: 22.2%
  44. Iowa: 18.7%
  45. Mississippi: 18.3%
  46. Ohio: 18.1%
  47. West Virginia: 16.7%
  48. South Carolina: 16.3%
  49. Wyoming: 16.3%
  50. North Carolina: 16.2%
  51. Montana: 15.9%

19 Responses to “The City-States of America”

  1. Chaim February 3, 2011 at 11:52 am Permalink

    I don’t think I like this metric, mostly because of the inclusion of New York, which clearly has other major metropolises (metropoli?). The percentage is skewed (inappropriately, I would argue) by the enormous population of NYC. I would rather come up with some definition of a major metropolitan area (greater than 100K people? a threshold for population density?) and then look for states that only have one qualifying area. You’d probably still get Delaware, Rhode Island, and New Jersey (since the latter is basically just one giant spread out metropolis), but maybe not Colorado or Arizona, for instance.

  2. james f February 4, 2011 at 5:47 pm Permalink

    this is a cool map, thanks man, i’m enjoying thinking about it as a chaotic expression of environmental, macro-economic and political processes :)

  3. Tim February 6, 2011 at 1:31 pm Permalink

    As a resident of Honolulu, I find this interesting. In Honolulu’s case, the entire Island of Oahu is the City and County of Honolulu. The percentage you list (70.1%) of Hawaii’s population living within this county sounds right on the money. However, I would have to drive through very rural areas for an hour in order to reach some of the mid-sized and smaller population centers on the island. Without them included, the percentage of state population in this county would decrease dramatically. Which makes me wonder how many of the counties that encompass these major cities across the nation would be so large as to have a significant number of people living inside the county but for all intents and purposes outside the city? And how would that affect the overall picture of what you are describing?

  4. Samuel Arbesman February 6, 2011 at 6:03 pm Permalink

    @Chaim You’re right that there are other metropolitan areas in some of these states, but the idea is that they vastly dominate the other ones. However, a true city-state in the US should really only have one metropolitan area.

    @Tim Going by county is certainly an imprecise metric. However, an MSA is essentially defined as a group of counties, even if the population density in some parts is quite rural.

    @james f Glad you like it!

  5. gardener1 February 7, 2011 at 4:44 pm Permalink

    Water.

    Not necessarily coastal access, but within immediate proximity to navigable and/or large potable water supply.

  6. Carl Holmberg February 7, 2011 at 5:33 pm Permalink

    @Chaim, as a former resident of Tucson, AZ, it was apparent that the Phoenix metro area utterly dominates the state’s politics and economy.
    @Tim, as a current resident of Maui, I’ll note that the Honolulu and Ewa subsections of Honolulu County totaled 644607 for 2010, nearly half the state… so the townies POV still carries a lot of weight.

  7. Susan February 8, 2011 at 3:48 pm Permalink

    Useful information from a traffic congestion management perspective. I will definitely use this!!!

  8. Swift Loris February 11, 2011 at 1:22 pm Permalink

    @Chaim–“Delaware, Rhode Island, and New Jersey (since the latter is basically just one giant spread out metropolis)”

    Er, no. Whole lot of open space in New Jersey–farmland, pine barrens, wetlands, even much of the shore area in the south is fairly sparsely populated. The state as a whole is very densely populated on average, but the dense areas are concentrated in the northeast and around Philly. See the map:

    http://en.wikipedia.org/wiki/File:New_Jersey_Population_Map.png

  9. MinchinWeb March 9, 2012 at 11:59 am Permalink

    I guess it depends how the census cuts the area between population nodes. In Utah, most of the population is concentrated along the Wasatch Front, including Ogden, Salt Lake, and Provo (see this map of population density). However, geography (mountains, lakes) make it easy to draw a line between the three and make them separate metropolitan areas, even if they increasing function as one. For example, FrontRunner, the commuter train in Utah, currently runs from Salt Lake to Ogden and is being expanded to Provo. Furthermore, the US Census Bureau has define a “Combined Statistical Area” that includes Salt Lake, Ogden, Heber, and Brigham City.

    So (just) Salt Lake: population of 1,124,197 or 39.9% of the state (so the figure you give above)
    Salt Lake, Ogden, et al. (Combined Statistical Area): 1,744,886 or 61.9%
    Wasatch Front (Salt Lake, Ogden, and Provo): 2,271,696 or 80.6%

  10. ConnGator March 9, 2012 at 12:13 pm Permalink

    Wait, there is only one city in Rhode Island and it covers the entire state? Wha?

  11. Jake T March 9, 2012 at 10:18 pm Permalink

    As a non-Chicago Illinois native, I can vouch for this idea. Illinois is, unfortunately for most of us who care for neither corruption or choking traffic, dominated overwhelmingly by Chicago.

  12. Aaron March 15, 2012 at 9:58 am Permalink

    This seems to have more to do with arbitrary state boundaries compared to city/metro area sizes than with the existence of bona fide city-states within the United States and probably speaks more to the suburban, sprawled nature of our growth patterns.

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