The New York Times is doing some interesting work around the “Shrinking Middle Class.” This piece demonstrates the shift away from middle-income and shows the exit of money from the city to the suburbs, and the increase in both affluent and poor neighborhoods at the expense of middle-income.
The NYTimes piece doesn’t animate the shift and it really bothered me because a graphic like this should so obviously be an animation. So I made one myself. (Dark green is most affluent, dark purple is the most poor.)
Philadelphia county becomes markedly more purple in 40 years. Notice also that almost no regions show any reversal of trends — green gets greener, or purple gets purpler.