In their book, Suspect Citizens, Frank Baumgartner and his colleagues looked at a massive amount of police stops in North Carolina over a number of years. The findings shed light on the nature of police stops and one of the remarkable features is that the findings have held outside of North Carolina as well.
In short, Black and brown drivers are disproportionately stopped. When they are stopped, they are disproportionately having their vehicles searched. When they have 
their vehicles searched, they are slightly less likely to have contraband found on them.
More importantly, the overall hit rate for finding contraband is extremely low, calling into question the justification of using traffic stops as pretexts for broader criminal investigations.
Listen as Frank Baumgartner, a social scientist, discusses the data and ways that racial profiling overall impacts policing, and police violence.
