States that have fewer restrictive gun laws on average see more mass shootings, according to a new study published Wednesday from Columbia University’s Mailman School of Public Health.
The study found that states with more permissive gun laws had mass shooting violence that was 11 percent higher.
“Our analyses reveal that U.S. gun laws have become more permissive in past decades, and the divide between permissive states and those with more stringent laws seems to be on the uptick in concert with the growing tragedy of mass shootings in the U.S.,” said study co-author Charles Branas, chair of the school’s Department of Epidemiology, in a statement to Fast Company.
The researchers took data from the Uniform Crime Reporting System at the Federal Bureau of Investigation and tallied the number of shootings where four or more people were killed. They cross-referenced that with several editions of the book “Traveler’s Guide to the Firearms Laws of the Fifty States.”
The study found that gun laws have leaned more permissive between 1998 and 2014 and domestic and non-domestic shootings varied depending on gun laws and locations.
The researchers said they need to do further studies to determine which laws led to more mass shootings.
“More studies that test the impact of specific state gun laws are warranted given our findings, the general increase in state gun law permissiveness, and the pressing need to stem the continued and increasing tragedy of mass shootings in the U.S.,” said lead author Paul Reeping, a researcher in the Department of Epidemiology.
The House in February passed a bill that would expand background checks to almost all firearm sales, but it is not expected to survive in the Republican-controlled Senate.