November 19, 2018
For the last several years, Nashville has made considerably more traffic stops per capita than the national average, with stops disproportionately involving black drivers. Here we examine the Metropolitan Nashville Police Department’s (MNPD) traffic stop practices in 2017, drawing on an extensive dataset of records provided by the department.
We find that black drivers were stopped 44% more often per driving-age resident when compared to white drivers; this gap is particularly pronounced among stops for non-moving violations (68%), such as broken tail lights and expired registration tags. These disparities stem, in part, from a strategy that concentrates traffic stops in high-crime areas. In particular, after controlling for location, disparities among non-moving violation stops drop from 68% to 37%.
This policy of concentrating stops in high-crime areas may be predicated on the belief that traffic stops are an effective tactic for reducing burglaries, robberies, and other criminal activity. We find, however, no immediate or long-term impact of traffic stops on serious crime. We further find that only 1.6% of stops result in a custodial arrest—often for license violations or drugs.
These findings suggest that the MNPD could reduce traffic stops without an associated rise in serious crime, while bringing Nashville’s traffic stop rates more inline with similar cities around the country. In particular, the MNPD could substantially reduce racial disparities by curtailing stops for non-moving violations. Notably, a small proportion of active MNPD officers conduct the majority of non-moving violation stops, potentially facilitating any effort to reduce such stops.