The map comes from the Regional Plan Association's America 2050 initiative. They have a small selection of other maps to choose from.
This is a beautifully-done map created by someone who clearly understands the power of gray. It is amazing how quickly the mind can recognize mountains from a few small blotches of the same shade of gray.
(Hat tip: DataViz)
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Earlier (though not nearly as cool): Megacities of the world [map]
