Lower 48

Ben Fry has created a stunning bit of visual data that is at once alluring and appalling. All Streets is an image of 26 million road segments across the lower 48 United States. The darker the line clusters, the higher the road (and thus population) density. Here you can see the entire U.S., as well as a close up of each coast with focal points on the San Francisco Bay Area and the Appalachian Mountains. It's worth the read to have a window into his process.