One big TN county has highest income inequality except New York's; another did best at equalizing

Lydia DePillis of The Washington Post wrote a very interesting story this week about Robertson County, Tennessee (Wikipedia map), because it has had the largest growth in income equality in the U.S. over the last five years among counties with at least 60,000 people, large enough for reliable analysis. That was caused by "a reduction in the number of people making very little money and in the number of people making lots of money," more commuting to Nashville and more manufacturing jobs, DePillis writes.

But we were more intrigued by a datum buried at the bottom of one of the charts with her story. The U.S. county over 60,000 with the greatest income inequality, except New York County (Manhattan), is another Tennessee county: Putnam. It straddles the Highland Rim and the Cumberland Plateau. On the plateau, where the coal gave out long ago, it is "very Appalachian," one regional observer told us. But down on the Highland Rim, there are many good-paying jobs at places like Tennessee Technological University and the headquarters of Averitt Express, a large trucking company. We suspect it also has dozens of millionaire entrepreneurs.

Putnam County in Tennessee (Wikipedia)

This seems to be a case where geology begets geography begets socioeconomics. We invite your observations.