Chicago's Vanishing Middle Class

The website, Sociological Images, explains the above map:

Borrowing data from education scholar Sean Reardon and sociologist Kendra Bischoff, Daniel Hertz calculated where the median family income of each Census tract fell relative to the entire metropolitan area. Orange tracts are ones where the median family income is 0-45% of the median for Chicago as a whole (struggling families), dark green tracts are ones where the median is 200% or more (resource rich families). Grey is, literally, middle class.