The City-States of America Reply

By Samuel Arbesman

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%

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