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. 2024 Jun 11;121(24):e2402547121.
doi: 10.1073/pnas.2402547121. Epub 2024 Jun 3.

The racial composition of road users, traffic citations, and police stops

Wenfei Xu  1 , Michael Smart  2 , Nebiyou Tilahun  3 , Sajad Askari  4 , Zachary Dennis  5 , Houpu Li  1 , David Levinson  5
Affiliations

The racial composition of road users, traffic citations, and police stops

Wenfei Xu et al. Proc Natl Acad Sci U S A. .

Abstract

This paper exploits the potential of Global Positioning System datasets sourced from mobile phones to estimate the racial composition of road users, leveraging data from their respective Census block group. The racial composition data encompasses approximately 46 million trips in the Chicago metropolitan region. The research focuses on the relationship between camera tickets and racial composition of drivers vs. police stops for traffic citations and the racial composition in these locations. Black drivers exhibit a higher likelihood of being ticketed by automated speed cameras and of being stopped for moving violations on roads, irrespective of the proportion of White drivers present. The research observes that this correlation attenuates as the proportion of White drivers on the road increases. The citation rate measured by cameras better matches the racial composition of road users on the links with cameras than do stops by police officers. This study therefore presents an important contribution to understanding racial disparities in moving violation stops, with implications for policy interventions and social justice reforms.

Keywords: Chicago, Illinois; camera enforcement; police stops; racial bias; traveler behavior.

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Conflict of interest statement

Competing interests statement:The authors declare no competing interest.

Figures

Fig. 1.
Fig. 1.
Speed cameras, ticketing intensity by race and census tract racial composition. Each dot is a speed camera and sizes correspond to the ratio of proportion of tickets to Black drivers to proportion of tickets to White drivers. The underlying map shows the proportion of population that is Black or African American by census tract.
Fig. 2.
Fig. 2.
Proportion of link traffic flow and tickets by race (from cameras). Each camera is represented by two points, once for each race group.
Fig. 3.
Fig. 3.
Stop share by race and street racial composition. All links are shown with small dots and links with cameras shown with large dots.) The probability of a Black driver being stopped (the green line) exceeds the probability of a White driver being stopped (purple line). The probability of a Black driver receiving a camera ticket (blue line) exceeds that of a White driver receiving a camera ticked (red line) at all shares of travel on the road, but not by as much as police stops.
Fig. 4.
Fig. 4.
Percentage of Black, White, Asian, and Other Drivers or Passengers by Link in Chicago, IL.
See this image and copyright information in PMC

References

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