MEASURING THE EFFECTS OF SHOTSPOTTER ON GUNFIRE IN ST. LOUIS COUNTY, MO

Overview

Gunshot detection systems are used by policing agencies across the U.S. to detect incidents of firearms discharge. While agencies that adopt the technology hope that it can help them reduce gun violence and make communities safer, the technology can be quite expensive—costing several hundred thousand dollars or more per year to maintain.

To assess the costs and benefits of implementing one gunshot detection system, ShotSpotter technology, the Policing Project and lead social scientist Jillian Carr (Assistant Professor, Krannert School of Management, Purdue University) partnered with the St. Louis County Police Department to compare geographic areas with and without ShotSpotter and determine whether there was a change in relevant public safety outcomes due to its adoption.

Highlights

1). In areas of St. Louis County that used ShotSpotter technology, police were alerted to four times as many gunshot incidents during the study period than in comparable areas without, making police aware of gunfire they would not have known about without the system.

2). Across the eight police beats with ShotSpotter, reported assaults, which include gun-related assaults, declined by about 30 percent following the implementation of the technology relative to comparable areas without it.

3).The number of overall arrests was unchanged by the implementation of ShotSpotter. There is no evidence that the technology exacerbated racial disparities in arrest patterns.