Are U.S. Crime Rate Trends Historically Contingent?

Abstract

Conventional explanations of crime rate trends assume that changes in the rates follow a process that is linear and constant, and that draws its inputs from a normal distribution. These features ensure that the present is linearly predictable from the past and that the future will be linearly predictable from the present. Questioning the conventional assumptions, an emerging class of historical contingency theories stresses variation in the crime-generating mechanism. According to contingency explanations, the process underlying the rates is nonlinear or non-normal, or has a structure that shifts over time. Future rate changes can then differ greatly depending on current conditions, and unanticipated developments will limit the accuracy of linear predictions. This article examines U.S. crime rates during the past two-thirds of the twentieth century, and finds little evidence of historical contingency. This supports the standard explanations, but it also raises deeper questions about the forces that produce the rates.