Using rarely accessible data from the criminal justice system, the Spatial Information Design Lab and the Justice Mapping Center have created maps of these “million dollar blocks” and of the city-prison-city-prison migration flow for five of the nation’s cities. The maps suggest that the criminal justice system has become the predominant government institution in these communities and that public investment in this system has resulted in significant costs to other elements of our civic infrastructure — education, housing, health, and family. Prisons and jails form the distant exostructure of many American cities today.