Recently, Jim Macklin posted:

see http://quickfacts.census.gov/qfd/states/20/20071.html
and then browse to find useful info. For instance Greeley
Co. Kansas has 2 people per square mile.

Well, if the county is 1,000 square miles, and all 500 people reside in a
two block neighborhood, then some areas will be densely populated! ;-)

Neil