Population density: http://www.mapofusa.net/us-population-density-map.htm http://www.mapofusa.net/us-population-density-map.htm There is obviously some correla

Population density: http://www.mapofusa.net/us-population-density-map.htm http://www.mapofusa.net/us-population-density-map.htm There is obviously some correlation. I find it hard to tell just by looking how much of the variance that explains.