Interesting. I made other map, pretty simple:
Population Density (People per square mile):
I'm also working on nationwide map that displays the average income by county; the progress can be viewed here:
http://www.maxairitsas.com/medianhinc.bmp
The density might also be more informative at the county level. For instance, in IL the seven counties in the Chicago area make up 7% of the state area but together have a population density twice that of NJ. The remainder of the state would have a pop density about the same as neighboring MO.
