Concentration Effects: A Natural Experiment of Neighborhood Change

David S. Kirk, University of Texas at Austin

Ex-prisoners tend to be geographically concentrated within resource-deprived sections of metropolitan areas. Despite a rich research tradition in the social sciences of examining the causes and consequences of concentration effects, particularly poverty, there is a dearth of empirical research on the subject of de-concentration generally, and on neighborhood changes in the spatial concentration of criminals specifically. This study aims to remedy this shortfall by exploiting a natural experiment — Hurricane Katrina — to examine how neighborhood changes in the concentration of parolees affects parolee recidivism rates. Findings reveal that an increase in the concentration of parolees in a census tract leads to a significant increase in the tract recidivism rate. Thus, concentration effects undermine the ability of parolees to avoid further incarceration. Releasing large numbers of ex-offenders into the same neighborhoods adversely affects the very public safety that criminal justice policies in the United States were designed to protect.