Wonder how closely that is to a map of federally owned lands?
There's some commonalities, especially in western states. http://www.terrierman.com/fedlands.JPG But there's a lot of uninhabited land in Texas and states north of it that doesn't have a lot of federal land. Similarly, Maine is largely empty, but not much Federal land. Discrepancies between how Census blocks are delineated vs. property boundaries may have something to do with the differences.