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Diffusion Processes in Homicide

NCJ Number
Date Published
16 pages
This study examined the role of gun availability in rising youth homicide rates in the late 1980's, the diffusion from juvenile involvement in drug markets to juvenile homicides during the mid-1980's, the spatial diffusion of homicide within a city, the role of youth gangs in the spatial diffusion of homicide in one city, the diffusion of homicide to other youth, and the rise and decline of youth homicide rates from 1985 through 1998.
This study involved a literature review of relevant research that involved national data as well as cross-city and within-city analyses. It concludes that the primary factor in the increase in youth homicides in the mid-1980's was greater access to handguns by youth. Across different cities, the increase in youth homicides followed the rise in youth involvement in crack markets by about 3 years. At approximately the same time, emerging new youth gangs in many cities became major participants in violence and the supplying of guns to their members. Further, this study concludes that crack markets and youth gangs contributed to escalating youth violence, both directly through the activities of participants and indirectly by serving as important vehicles for the diffusion of guns and the associated lethal violence to youth more broadly. Analyses of time trends in youth homicides at the national, inter-city, and intra-city levels found that declining rates were well underway by 1995. Such pervasive declines are compatible with the self-limiting processes that signal the waning of an epidemic. There is also clear evidence that the reduced use of guns was an important factor in the decline in youth homicides by the mid-1990's; however, these effects were confounded by mutual influences of changing drug markets (fewer new users) and participation in youth gangs. Another factor was a robust economy that provided legitimate jobs for inner city youth who might have otherwise been recruited into the drug industry. 12 references

Date Published: January 1, 1999