There is a term in the marketing business... well, probably other businesses as well... used to refer to the middle part of the country, between the coasts. This term is "Flyover Country." It's very demeaning, of course; it's a way of saying the only thing you do in that part of the country is fly over it--from New York to LA, say.
The map today is a fairly visible example of why the middle of the country is called that. If you're in the marketing biz, you want to do your biz where there are the most dollars for you to vacuum up. In other words, you want to appeal to the people and places that have the bucks, and you'll just ignore every place else.
Our first map was of population density. The most recent one was of household income. This map combines those two: I divided each county's population by the average size of a household in that county to get an approximation of the number of households per county. Then I multiplied the number of households by median household income. It's not perfect, but we're presented here with a map showing roughly the number of dollars in private hands in each county. Obviously this ignores corporate profits and holdings and doesn't even try to describe the size of personal savings. Instead, this map shows how many dollars are taken home by private citizens in each county each year. I call it the Dollar Dens-o-Map, the density of dollars on the ground. That light colored part in the middle? Yeah, that's why they call it "flyover country."