Traffic Stops

The rate of traffic stops by St. Louis City police officers per 1,000 residents of driving-age

Equity Score
Indicator scores are represented on a scale from 1 to 100.
Disparity Ratio
Disparity direction: black-white
Traffic stops made by St. Louis City police

Black drivers are nearly twice as likely to be stopped by police officers as white drivers.

Source: Missouri Attorney General's Office; American Community Survey 1-year PUMS

A score of 100 represents racial equity, meaning there are no racial disparities in outcomes. The lower the Equity Score, the greater the disparity.

For Traffic Stops, a score of 100 — a score reflecting racial equity — would mean black and white drivers are equally likely to be stopped by police. It is important to note that for this indicator, racial equity is not our only goal: we also want to improve outcomes for all.

More Information

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What does this indicator measure?

Traffics Stops measures the rate of traffic stops by St. Louis City police officers per 1,000 residents of driving-age. Traffic stops are interactions in which a police officer stops a motorist to investigate a traffic violation or other crime. There were a total of 51,806 traffic stops made by St. Louis police in 2016, which translates to a rate of 200.2 stops per 1,000 driving-age residents. 

Traffic Stops analysis

Traffic stops made by St. Louis police in St. Louis City.

  All Black White Disparity Ratio Equity Score
Traffic stops 51,806 32,356 17,762 - -
Drivers: Residents of driving age (15+) 258,821 114,872 121,093 - -
Traffic stops per 1,000 drivers 200.2 281.7 146.7 1.920 to 1 44

Data source: MO Attorney General’s Office, 2016; American Community Survey 1-year PUMS, 2016.

Data Note: These are traffic stops made by SLMPD and do not include stops by Missouri State Highway Patrol. The Missouri Attorney General’s Office does not yet report what share of drivers stopped by SLMPD are city residents or are from outside the region.

What does this analysis mean?

Black drivers are nearly twice as likely as white drivers to be stopped by police while driving. Black drivers are the most likely to be stopped while driving with a rate of 281.7 stops per 1,000 drivers, followed by white drivers with 146.7 stops per 1,000 drivers. Non-black, non-white drivers were stopped a total of 1,668 times, for a rate of 61.8 stops per 1,000 drivers. If the traffic stop rate were equitable, black drivers would have been stopped 15,413 fewer times. 

Traffic stops are sometimes accompanied by searches and/or arrests. Officers are required to arrest if they discover a driver has a bench warrant, which is a warrant issued when a defendant fails to appear in court after receiving a summons with a specific court date. Outstanding bench warrants are the most common reason for arrest during traffic stops.

Secondary Impacts of Traffic Stops in St. Louis City
  Black White
Stops 32,356 17,762
Searches 2,603 (8.0% of stops) 1,026 (5.8% of stops)
Found with contraband 375 (4.4% of searches) 184 (17.9% of searches)
Arrested 1,253 (3.9% of stops) 388 (2.2% of stops)

Data source: MO Attorney General’s Office, 2016.

During traffic stops, black drivers are searched more often than white drivers. Black drivers are also more frequently arrested during traffic stops than white drivers. However, white drivers are more likely to be found with contraband when searched than black drivers.

Why do Traffic Stops matter?

Traffic Stops is an indicator that illustrates the disparate impact of policing on minority communities. Black drivers are almost twice as likely as white drivers to be pulled over in the City of St. Louis. They are also more likely to be searched after a stop and more likely to be arrested — even though they’re less likely than whites to be found carrying contraband when searched. According to the Stanford Open Policing Project:

In the 1950s, the Nobel prize-winning economist Gary Becker proposed an elegant method to test for bias in search decisions: the outcome test.

Becker proposed looking at search outcomes. If officers don’t discriminate, he argued, they should find contraband — like illegal drugs or weapons — on searched minorities at the same rate as on searched whites. If searches of minorities turn up contraband at lower rates than searches of whites, the outcome test suggests officers are applying a double standard, searching minorities on the basis of less evidence.

The Stanford Open Policing Project points out that “disentangling discrimination from effective policing is challenging and requires more subtle statistical analysis.” Still, patterns of racial disparity make traffic stops more than an inconvenience. Inequitable enforcement of laws contributes to tension and distrust between police agencies and the communities they serve. 

Which Calls to Action from the Ferguson Commission report are linked with this indicator?

The Ferguson Commission’s calls to action related to traffic stops include:

Questions for further investigation

  • What proportion of traffic stops are of residents of St. Louis?
  • Why is there a racial disparity in Traffic Stops? 
  • What can St. Louis do to reduce racial disparities in Traffic Stops?
  • What initiatives are currently underway to reduce racial disparities in Traffic Stops?

How can I learn more about this issue?

The Stanford Open Policing Project has collected and standardized more than 100 million records of traffic stop and search data from 31 states.

Through its work with the Research Network on Misdemeanor Justice, the University of Missouri-St. Louis, in collaboration with the City of St. Louis, released its 2018 report, "Tracking Enforcement Rates in the City of St. Louis, 2002-2017." The goal of the Research Network is to use the power of data analytics to inform policy conversations and reform the enforcement of lower-level offenses such as misdemeanors, citations/summons, and pedestrian and traffic stops. 

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