Examining Space–Time Interaction in City-Level Homicide Data: Crack Markets and the Diffusion of Guns Among Youth
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- Cork, D. Journal of Quantitative Criminology (1999) 15: 379. doi:10.1023/A:1007540007803
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This paper examines the linkage between crack market activity and gunhomicide suggested by Blumstein (1995), who argues that the arrival ofcrack stimulated an increased availability of guns among juveniles. Thisgreater availability of guns, the argument continues, is responsible for thesharp upswing in juvenile homicide experienced in the United States in themid-1980s. Using city-level data on crack arrests and gun-related juvenilehomicide, we fit a change-point version of the Bass (1969) model ofinnovation diffusion. We find that, in most large American cities, thediffusion process for crack cocaine experienced an onset of dramatic growththat was followed by a similar, slightly slower growth in gun homicidescommitted by juveniles. We further use cluster analysis to find that thespatial patterning of the two processes is similar, starting on the East andWest Coasts and working their way toward other regions of the nation. Gunuse in homicide among slightly older offenders (ages 18–24) alsoexperienced a change at roughly the same time as the juveniles, but the rateof diffusion was considerably milder than for the younger group; offendersages 25 or older generally show no growth in gun-related homicide whatsoever. In addition, there is no detectable surge in juvenile nongun homicide activity. Based on these findings, we conclude that the crack cocaine markets–gun availability linkage is highly plausible, and we suggest directions for future research in clarifying the dynamics of the late-1980s surge in juvenile homicide.