I commend the Economic Innovation Group for using median income rather than mean income to create their Index of Distressed Communities. They created a beautiful map of their Distressed Community Index where the old slave states and rural areas of the sun belt look particularly distressed. I’m not sure how much they weigh median income relative to the other components of their index (education, unemployment, poverty, and business growth), but at least they didn’t use mean income like most people do.
One bad decision EIG made in constructing their index is to compare the median income in each colored region to the state median income. This reduces the comparability of one state to another. For example, the border between North Carolina and Virginia shows greater economic distress on the Virginia side of the border, but this is probably an artifact of EIG’s bad methodology. The median income in rural counties in Virginia are compared with the high median state income ($64,900) whereas the adjacent rural counties across the border in North Carolina are compared with the low median income for that state ($46,600). As GEOFRED shows, the old slave states would look even redder in AIG’s index if the median income in each region were compared with the median income for the US as a whole:
Another way EIG could improve their index is by creating a second map to also display each region with an area proportional to its population. All of the big splotches of area on the map have very little population and because we care about people more than land, it makes more sense to weigh each area of land by the population. They could either preserve the basic outlines of each state by squeezing each region into the state as in this map…
…or they could adjust the size of each region by its population which would make it look more like this map.
This is truly the most realistic way to represent the distribution of economic distress in the US. The only reason we don’t use it is the lack of imagination by people like the EIG and the momentum of tradition. Both problems will go away once people get used to seeing this kind of cartogram. It is a much more realistic way to map the US population.