Aaron Renn

Cities: networks or size?

Aaron M. Renn is The Urbanophile, an opinion-leading urban affairs analyst, consultant, speaker, and writer., Sep 20, 10.

Tagged with networks, place theory, size

When we hear people discuss the cities that are adjusting well to the demands of the new economy, it is frequently the largest cities that are touted: New York, Chicago, London, etc. At a minimum, these places tend to be “of a certain size.”

Zachary Neal, a professor of sociology and global urban studies at Michigan State, has a new study out that disputes this. Entitled “From Central Places to Network Spaces,” it makes the argument that networks rather than size are the critical determinant of urban success in the current economy:
At the beginning of the twentieth century, many urban economies in the United States depended primarily on factors located within the city and its adjacent hinterland, thus situating cities in a size-based hierarchy like that described by central place theory. However, by the end of the twentieth century, technological innovations and economic restructuring led urban economies to depend more on factors located between cities, namely, the relationships among cities that permit the exchange of key resources and allow the development of interurban cooperation and economies of scale. This transition implies the emergence of a newer, more network-based hierarchy in which the dominant cities at the top of the hierarchy are those which serve as “basing points” for resources flowing through intercity networks.

Since, like most academic studies, this one is painful to read, you may prefer to check out an essay version Neal posted to New Geography.

The size based notion of an urban hierarchy was rooted in central place theory, where cities’ size, economic clout, and amenities depended on the size of their hinterlands. The author notes that this worldview may have had more accuracy in the early 20th century, when huge cities such as Detroit and Philadelphia, were among the nation’s most important.

But during the 20th century, size and hinterland decreased in importance and the networks that cities participated in became more important. Some cities such as Chicago and New York retained high rankings in both cities, but it was because they either had or developed the networks that were relevant to the 20th century. Cities like Detroit, Cleveland, and Pittsburgh – Neal’s examples – failed to develop these networks and so became what he dubbed “offline metropolises.”

Conversely, places that previously would not have ranked highly in the size based world, such as North Carolina’s Research Triangle or Bentonville, Arkansas, can, by developing networks, become important economic nodes.

It’s an interesting viewpoint, though I think the use of Bentonville points out a weakness. Bentonville owes its status almost entirely to Wal-Mart. If Wal-Mart departed tomorrow, no more Bentonville. Wal-Mart may have networks, but Bentonville is only borrowing them. The same might be true of any company town or even university town. The economic structure of these towns only changed to the extent that they got lucky with one major institution.

Jim Russell seizes on these findings to question the idea of the megaregion, which he sees as a relic of central place theory and industrial age thinking.

The Case for Size

While Neal pooh-pooh’s size, other researchers have pointed to its virtues. This 2007 article in SEED magazine discusses the work of Geoffrey West, Jim Brown, and Brian Enquist who did research into testing whether the effect of greater metabolic efficiency found in larger animals also applied to cities. Their conclusion was that it did:

After analyzing the statistics, the answer was clear: Cities are like elephants. They get more economical with size. It doesn’t matter whether the city is located in China, Europe, or the American Midwest; every city is simply a scaled version of the same city. In metropolis after metropolis, the indicators of urban “metabolism”—like the per-capita consumption of gasoline or the surface area of roads or the total length of electrical cables—scaled to an exponent of (population)0.8, which is very similar to the biological equivalent of (mass)0.75. This means that a city can double its population without doubling its resource consumption. “One of the basic principles of cities is that it’s more efficient to bring people together,” West says. “You need a little bit less of everything per person. It’s the exact same way in biology. As animals get bigger, they require less energy to support each unit of tissue.”

So while the authors do not predict success, they do indicate that there are efficiencies from scale – a conclusion opposite from some who have suggested large cities are in fact inefficient.

Other researchers have also found differences based on city size. Jim Russell pointed me at recently released research paper called “Spatial Sorting”:

In this paper we show that there is indeed evidence that disproportionately more skilled citizens locate in larger cities. However, we provide a key new insight: larger cities also disproportionately attract lower skilled agents. And it turns out that large cities like New York and Detroit in that respect are more similar to each other than to small cities.

The “fat tails” the authors find for larger cities show that they differ in another important way from smaller ones. Given the strong evidence linking college degree attainment and high skill labor to urban success, perhaps this explains more than networks the relative success of the places Neal discusses (e.g., Wal-Mart recruits lots of people with degrees to Bentonville).

My own take is that there are benefits to size in some cases. For example, a certain minimum scale is a prerequisite to being able to support certain activities. Want to have a major airport or a pro football team? Better be big enough to support them. This is one legacy of central place theory that hasn’t gone away. As size decreases, you progressively lose the ability to support more and more of the functions and amenities that the largest cities can simply by virtue of their market size and aggregate wealth. The internet (e.g., Amazon and iTunes) have reduced this somewhat, but not eliminated it entirely.

So it size generates economic efficiencies, attracts more talent, and enables you do potentially do more things, perhaps it does have utility. That’s not to say networks are unimportant. They are of critical importance. But size remains an important consideration as well.

What do you think?