The Concentration and Stability of Gun Violence at Micro Places in Boston, 1980-2008

Boston, like many other major U.S. cities, experienced an epidemic of gun violence during the late 1980s and early 1990s that was followed by a sudden large downturn in gun violence in the mid 1990s. The gun violence drop continued until the early part of the new millennium. Recent advances in criminological research suggest that there is significant clustering of crime in micro places, or hot spots, that generate a disproportionate amount of criminal events in a city. In this paper, we use growth curve regression models to uncover distinctive developmental trends in gun assault incidents at street segments and intersections in Boston over a 29-year period. We find that Boston gun violence is intensely concentrated at a small number of street segments and intersections rather than spread evenly across the urban landscape between 1980 and 2008. Gun violence trends at these high-activity micro places follow two general trajectories: stable concentrations of gun assaults incidents over time and volatile concentrations of gun assault incidents over time. Micro places with volatile trajectories represent less than 3% of street segments and intersections, generate more than half of all gun violence incidents, and seem to be the primary drivers of overall gun violence trends in Boston. Our findings suggest that the urban gun violence epidemic, and sudden downturn in urban gun violence in the late 1990s, may be best understood by examining highly volatile micro-level trends at a relatively small number of places in urban environments.