Control Cities

Ever wonder why certain towns wind up on highway signs and others do not? I used to think that any town that passed a certain population threshold would be listed on the map. While that may be the criterion for building an exit, today I discovered that there exist certain "control cities" that serve as distance references on our Interstates. Click on the title of this entry to link to a chart of these control cities and the Interstates with which they're associated! It's like taking a very fast cross country trip... Simultaneously, it makes me think of how large the country is, and how completely it is straddled by the Eisenhower Interstate System.