map of streets of americaCourtesy of my partner at eartotheground comes this amazing map of the United States by Ben Fry.  He describes his creation:

All of the streets in the lower 48 United States: an image of 26 million individual road segments. No other features (such as outlines or geographic features) have been added to this image, however they emerge as roads avoid mountains, and sparse areas convey low population.

This is a really artistic and thought provoking study of settlement in the United States.  Not only does this show where our population centers are but also gives us a notion of where sprawl is most pervasive.  For example, compare the size of the Houston area to the size of the Boston area.  The Houston area is far more spread out, which makes sense as Houston was founded on the basis of auto travel and Boston was first designed to accommodate nothing much faster than a horse.  However, these images of the pervasiveness of sprawl or lack thereof demonstrate the difficulties of establishing effective public transportation systems in many American cities.