As Daniel Kay Hertz explains, the goal of these maps is not merely to depress you (you’re welcome!), but to suggest just how dramatically the reality of Chicago’s “two cities” has changed over the last few generations, how non-eternal its present state is, and that a happier alternate reality isn’t just possible, but actually existed relatively recently.
Daniel Kay Hertz goes on to note, he feels relatively comfortable telling the story of how Chicago came to be so segregated by race; but is much humbler about his ability to explain this, except inasmuch as the ever-widening ghetto of the affluent could not exist without, yes, radically exclusionary housing laws.
One last piece: the obvious and immediate reaction to these maps is to see them as a direct consequence of rising income inequality. There is some truth to that, but the researchers from which much of this data came have already discovered that income segregation has actually risen faster than inequality. So that’s not the end of the story.
Anyway, here you go: the disappearance of Chicago’s middle-class and mixed-income neighborhoods since 1970, measured by each Census tract’s median family income as a percentage of the median family income for the Chicago metropolitan region as a whole.