|The great drop in crime that begain in the United States in 1991 was one of the most significant -- and unanticipated -- criminological events of the 20th Century. The reasons for the drop are ill-explored, to say the least. Almost everyone who discusses the issue interprets the drop to fit their favorite theory of crime, but empirical studies of the issues are harder to come by.
Chicago has been no exception to the crime drop story: since 1991 there has been a steady decline in virtually every category. The largest has been in robbery, which dropped by 58 percent between 1991 and 2001; robberies with a gun went down by 62 percent. Serious assault and battery declined by 40 percent, motor vehicle theft was down by 42 percent, and burglary dropped 50 percent. While crime rates were dropping nationally during the same period, the drop in crime in Chicago was noticeably greater in most categories.
This paper examines the reasons for this drop in crime, using data for small areas of the city. It tests claims about the role of drugs and gangs in the crime drop, the deterrent effect of traditional police practices and community policing, and the salutary effects of fixing broken windows. Because it is based on local-area time series, many important "macro" theories of crime causation, and perhaps drop, cannot be addressed. But "all crime is local," and this study has the advantage of disaggregating the analysis to the level at which it occurs and must be dealt with.
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