Here I have chosen to analyze the overly simplistic model of the US interstate system (found at the link below) in terms of graph theory. I feel that several insights about networks may be gain by such an analysis despite the oversimplification already noted. Each city should be viewed as a node and each highway as the connecting edge. The conclusions drawn here are obviously not fully representative of the many factors that determine a city’s commercial success, but rather interesting considerations to entertain.

This diagram comes from an artist, Chris Yates. http://www.chrisyates.net/reprographics/index.php?page=424

First, consider a concept such as betweenness. Dallas or Oklahoma City have large betweenness values in this graph which I will not attempt to calculate but would like to compare to other cities such as Fort Myers or Nogales. These two cites have a betweenness value of 0 and I personally rarely hear much about them. It is interesting to consider the possibility that Dallas’ and Oklahoma City’s large commercial success relative to Ft. Myers and Nogales may, in part, be the result of their large betweenness values. They are an intermediary in the route to numerous cites providing them with a large amount of commercial traffic; however, in the case of Nogales and Ft. Myers each of these cities must be a destination rather than a checkpoint.

Obviously, this cannot be true for all cities. San Diego for example has a betweenness value of 0, yet, as a city, it is a large commercial success. But, here it should be noted that
the graph only represents potential land commerce by way of the interstate system. San Diego is also home to an international airport and is a seaside city.

It is also interesting to examine this graph with regard to power relations within social networks. These are cites instead of people but they often interact, trade, and rely on one another in much the same ways that people do. Chicago is the intersection for six major interstates. Grand Rapids on the other hand has only two interstates to work with, 65 and 96. By comparison, Chicago is in a far more powerful position in terms of potential interstate commerce.

Most of the nations’ most powerful cities are found on this graphical representation. While much of this is by design, it is also indicative of the importance of connectivity for being a major center of commerce and industry. And, after all, it is a cool picture.