GREAT ARTICLE! Check out http://www.sciencenews.org/view/generic/id/62317/title/Most_prisoners_come_from_few_neighborhoods for a write-up, subtitled, "'Incarceration Hot Spots' Inculcate a Vicious Brand of Hopelessness," of this new Harvard sociology paper.
My favorite quotes:
“Mass incarceration in the United States has a deep local concentration in relatively few disadvantaged communities,” Sampson asserted.
Chicago crime data for 1990 to 1995 show that a large majority of prison and jail populations came from two poor, black sections of the city, Sampson and Loeffler found. During that time, overall rates of crime and violence declined in Chicago while incarceration rates rose in those two areas.