Check Your 6 was one of hundreds of gun dealerships that opened across the United States between 2010 and 2017, notes a preprint study that was published last month on social science research website SSRN and has not yet been peer-reviewed. According to the study, which looked at county-level data nationwide over a 17-year period, when the number of gun dealerships within 100 miles of a given area went up, the number of gun homicides in that area also increased in subsequent years—even as nongun killings declined overall (see graphic). Majority-Black communities bore the brunt of that violence, the study found.

The sharp rises in gun violence seen in some Black communities since 2014 have been widely attributed to the “Ferguson effect.” This term was coined by the then-chief of the St. Louis police, who claimed violent crime increases were driven by officers’ deteriorating morale following nationwide protests of the 2014 police killing of unarmed Black teenager Michael Brown in the St. Louis suburb of Ferguson, Mo. But the study authors propose these increases are linked to a steep rise in gun dealerships specializing in handgun sales near majority-Black communities shortly before 2014.

Before 2010 there had been “a massive decline in gun dealers,” says study co-author David Johnson, an economist at the University of Central Missouri. “Three, four years later, you start seeing declines in homicides—and then they pop right back up again once those gun dealers start reentering the market.” It is unclear what might have caused the number of dealerships to drop ahead of 2010, but the rebound in gun sales may have been driven by fears that then-President Barack Obama would enact strict gun-control policies, according to a 2015 study published in the Journal of Public Economics.