The Missouri state attorney general’s office issued a report on the number of traffic stops made in the state and of the racial/ethnic background of the people pulled over.
This report summarizes the data from 606 law enforcement agencies in Missouri for calendar year 2017.
The data represents 97.6% of the 677 law enforcement agencies in the state. The agencies filing reports recorded a total of 1,541,755 vehicle stops, resulting in 99,441 searches and 73,193 arrests.
The analysis of data uses a disparity-index. According to the report, a disparity index value above 1 indicates that a group accounts for a higher proportion of traffic stops than its percentage of the population alone would predict. And a disparity-index value below 1 indicates that a group accounts for a lower proportion of traffic stops than its percentage of the population alone would predict. For example, the 1,189,744 Whites drivers who were stopped accounted for 77.2% of all traffic stops in 2017. Whites comprise an estimated 82.8% of Missouri’s driving age population. The disparity-index value for Whites is, therefore, .93 (i.e., .772/.828). Whites drivers were stopped, in other words, at slightly below the rate expected based on their fraction of the driving-age population from the 2010 Census.
The results were not the same for several of the other groups. The report states that African-Americans represent 10.9% of the driving-age population but 18.7% of all traffic stops, for a disparity-index value of 1.72. African-Americans were stopped at a rate 72% greater than expected based solely on their proportion of the driving-age population. Hispanics, Asians, American Indians, and persons of mixed or unknown race were stopped at rates well below their proportion of the driving-age population. The values on the disparity index for the different groups can be compared directly to one another. For example, the rate at which African-American motorists were stopped is 1.85 times that of the rate at which White motorists were stopped (i.e., 1.72/.93). In other words, accounting for their respective proportions of Missouri’s driving-age population, African-Americans were stopped at a rate 85% higher than Whites.