Explaining the Long Trend in Chicago’s Homicide Clearance Rate, 1965-2022 - CANCELLED

• In Event: Understanding Patterns and Trends in Clearance of Lethal and Non-lethal Criminal Victimization

Abstract

Chicago’s homicide arrest rate dropped from 91% in 1965 to 35% in 2000 and has remained relatively low since then. This pattern mirrors the trend in the national homicide clearance rate. A plausible explanation for this Great Decline is the profound change in homicide case mix, which arguably has made it intrinsically more difficult to solve homicide cases. Our analysis describes the change in case mix and the arrest rate for the period 1965 to 2020, all by use of a unique homicide case microdata set. We document the large changes in case mix: for example, the percentage of all homicides in which a male victim was shot outdoors increased from 18% (1965) to 69% (2020). However, this shift in case mix alone does not account for Chicago's earlier Great Decline, as indicated by our novel Arrest Rate Index. In fact, the arrest rates in each of the categories defined by location, sex, and weapon type exhibited similar declines through 2000. Our preferred explanation for the Great Decline is that the operational standard for making an arrest increased during this period. That interpretation is well supported by evidence explaining the corresponding national trend (Cook & Mancik, 2024), though direct evidence is lacking for Chicago. This interpretation challenges the use of the arrest rate as a police performance indicator and offers a positive interpretation of the Great Decline.

Authors

• Philip Cook, Duke University

• Javier Lopez, The University of Chicago Crime Lab