The western US is incredibly sparsely populated compared to the east. Just look at one of those nighttime satellite shots: http://geology.com/articles/night-sat

The western US is incredibly sparsely populated compared to the east. Just look at one of those nighttime satellite shots: http://geology.com/articles/night-satellite/satellite-photo-united-states-at-night-lg.jpg http://geology.com/articles/night-satellite/satellite-photo-...