In May 2014, the Mayor’s Office turned to the Crime Lab for support in its efforts to better understand Chicago’s gun violence problem, with the ultimate goal of crafting smart policy and investing in strategies likely to make a difference. With analytic support from the Crime Lab, the Mayor’s Office published a report entitled Tracing the Guns, which mapped the flow of guns into Chicago, detailed the initial sources of guns recovered at crime scenes, and compared Chicago to other major cities. The report also identified promising gun enforcement strategies. 

Among the notable findings explored in the report was the fact that the Chicago Police Department recovers more guns per capita on the streets of Chicago than the NYPD and LAPD combined. Efforts to understand where these guns are coming from are critically important to informing CPD’s strategy to address this problem, especially because all guns in Chicago come by definition come from outside city limits as there are no licensed gun stores in the city. To assist the Department, the Crime Lab used trace data from the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) to track the source of guns used in crimes. While CPD routinely uses these data to investigate individual shooting cases, detectives are not generally able to analyze information across the caseloads of different officers due to insufficient time and resources, which prevents the potential identification of larger patterns showing how illegal guns wind up Chicago. Our analyses revealed that many of the guns used in crimes in Chicago were first purchased in Indiana, which helped focus interstate anti-trafficking initiatives on reducing the flow of guns from that source. Crime Lab analysis also identified the specific suburban Cook County gun stores responsible for selling large numbers of guns that ultimately wound up being used in Chicago crimes; for example, our calculations showed that between 2009 and 2015, CPD recovered 848 guns originally sold at just a single store in Lyons, IL. These findings contributed to a new ordinance passed by the Lyons Board of Trustees to more closely monitor local gun dealers, including video monitoring at point of sale and outside the shop.

In response to the surge in gun violence in the city in 2016, the Mayor’s Office asked the Crime Lab to support its effort to update the original 2014 Tracing the Guns report. In addition to updates to the original, the 2017 version included new analyses and offered recommendations informed by the best available evidence and data around the most promising strategies for illegal gun enforcement ideas to guide policy and practice. 

To read the 2014 Tracing the Guns report click here.

To read the 2017 Tracing the Guns report click here.

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