I imagine these correspond to highways. I did a similar thing a while back with postal codes and their density. I don't know why I was so blown away, but I was.

I imagine these correspond to highways. I did a similar thing a while back with postal codes and their density. I don't know why I was so blown away, but I was. Take the West Coast for example: http://i.imgur.com/WBzWG.png http://i.imgur.com/WBzWG.png