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 began as an example I created for a student in the fall of 2006, and I just recently got a chance to document it properly.
Alaska and Hawaii were initially left out for simplicity's sake, but I felt guilty because of the sad emails received from zipdecode
visitors. Unfortunately, the two states don't "work" because there aren't enough roads to outline their shape, so I left them out permanently. More technical details can be found here
and additional updates here
A detail of the West shows the relative lack of roads in mountainous areas, punctuated by the densely populated Bay Area.
The white blocks seem to be rural routes and unnamed roads, their alignment to lat/lon boundaries suggests differences in how adjacent counties identify streets.
Original image of the lower 48 states.
The ridges of the Appalachian mountain range emerge from the roads that avoid them (or follow their contours).