In North Carolina, young black men are twice as likely to be stopped in their car than white men. In some U.S. cities, including Chicago, the ratio is much higher.
Frank Baumgartner, a political science professor at UNC-Chapel Hill, studies traffic stop statistics across the country. For North Carolina, he pulls his data from a state-run database.
In recent years, a lot of attention has been paid to the disproportionate rate of African-Americans and Latinos stopped by police, especially with the highly publicized police-involved shootings of Mike Brown and Philando Castille, and death of Sandra Bland, following recorded traffic stops.
In 1999, the North Carolina General Assembly passed a law that mandates all police departments that serve municipalities with populations above 10,000 must submit data on all traffic stops to the State Bureau of Investigation for inclusion in a statewide database.
"North Carolina was actually the first state in the country to mandate that, after there was a lot of national attention to the concept of 'driving while black' or 'driving while brown,'" Baumgartner said.
This month, the Asheville City Council heard evidence that their city's police department may not be adequately tracking and reporting their officers' stops.
Ian Mance, an attorney at the legal advocacy group the Southern Coalition for Social Justice was invited by Asheville's local NAACP chapter to analyze the city's publicly available traffic stop data. Mance maintains the website, OpenDataPolicing.com, which visualizes the traffic stop data collected by the State Bureau of Investigation.
Mance says he has given reports and done very informal spot-check audits on other city's traffic stop data, including Charlotte and Durham, and found a few citations missing from the state database.
"It's not uncommon to encounter some stops that aren't reported. When you're a large department, you're reporting hundreds of thousands of stops a year. A ticket might end up between the car seats."
But Mance said he noticed that the number of reports from Asheville had dropped off significantly in recent years. So he conducted a slightly more extensive audit. Mance went to Asheville's county offices and randomly selected 50 traffic tickets and checked them against the SBI database. He says more than half did not show up in the state's database.
"I don't know how representative my sample was of the [state] database as a whole. And if the number is large, obviously that would be a cause for concern," Mance said.
Asheville Mayor Esther Manheimer says she's also concerned. According to Manheimer, the Asheville Police Department's speed radars were malfunctioning for some of that time period, but it's not clear that technical error accounts for all of the missing citations identified. Asheville Police Chief Tammy Hooper will look into the issue and report back at the city council's next regularly scheduled meeting.
Baumgartner says if it's true that Asheville didn't report many of its traffic stops, then it's possible other departments have also failed to do so. He says that's concerning because racial disparities in known stops are already troubling.
"If police are mandated by the state to report every traffic stop, and if they're not doing it, then there definitely needs to be some kind of investigation and sanction for departments that are not in compliance with the law," Baumgartner said.
Mance says there is currently no evidence that other police department may be failing to submit data. But, he and Baumgartner say it would be possible because there is relatively little oversight of submission.