When gun shows are held in Nevada, gun-related deaths and injuries spike across the state line in California for at least the next two weeks. A new study by UC Berkeley researchers examined gun deaths and injuries in California before and after gun shows in California and Nevada, and their results show a nearly 70 percent increase in deaths and injuries from firearms in California communities within convenient driving distance of Nevada gun shows. No spike in gun deaths or injuries was found following gun shows in California.

More than 4,000 gun shows are held annually in the U.S., and gun shows account for 4 to 9 percent of annual firearm sales. Some gun shows draw thousands of attendees and hundreds of sellers, whose transactions may not be subject to vigorous oversight. Some of these transactions are between private parties and do not involve a background check. Research has shown that firearms from gun shows are disproportionately implicated in crimes. California has some of the strongest firearm laws in the country, including a comprehensive set of statutes regulating gun shows. Nevada has some of the least restrictive firearm laws in the country and no explicit regulations on gun shows.

“Our study suggests that California’s strict regulations — on firearms, generally, and on gun shows, specifically — may be effective in preventing short-term increases in firearm deaths and injuries following gun shows,” said the study’s lead author, Ellicott Matthay, a Ph.D. student in UC Berkeley’s School of Public Health.

The study was funded in part by the National Institutes of Health (NIH), through a NIH Director’s New Innovator Award to Jennifer Ahern, associate professor of public health at Berkeley and the study’s senior author. Additional funding was provided by the Heising-Simons Foundation. Garen Wintemute, of the Violence Prevention Research Program in the Department of Emergency Medicine at UC Davis, collaborated on the study. It will be published online on October 24 in the journal Annals of Internal Medicine.

The study identified 275 gun shows in Nevada (mostly in Reno and Las Vegas) and 640 gun shows in California between 2005 and 2013. No publicly available database of gun shows exists for either state, so the researchers combed through trade publications to identify the dates and locations of gun shows.

Gun shows in Nevada were associated with increases in firearm deaths and injuries in California communities within convenient driving distance. California gun shows, in contrast, were not associated with local, short-term increases in firearm deaths and injuries. Non-firearm injuries served as a negative control and were not associated with California or Nevada gun shows.

Compared to the two weeks before the gun shows occurred, post-show firearm injury rates remained stable in regions near California gun shows. But post-show firearm injury rates increased from 0.67 per 100,000 people to 1.14 per 100,000 in regions near Nevada shows. This 70 percent increase translates to 30 more firearms deaths or injuries in California near the state line after 161 Nevada gun shows.

“The area of California that borders Nevada is sparsely populated, and over the study period there were relatively few Nevada gun shows. However, there are thousands of gun shows in the United States each year, most of them in relatively unregulated states. If we extended this study nationwide, it is possible that the number of deaths and injuries associated with gun shows would be far greater,” Ahern said.

Unlike firearm purchases through federally licensed dealers, private transfers of a gun from one person to another do not require background checks in many states. Gun shows make private transfers easier by drawing large crowds together for the purpose of buying and selling guns. During the study period, California required background checks on all transfers, including private transfers, but Nevada did not. (Nevada voters approved a private gun sale background check requirement in November 2016, but it has not been implemented.)

“The study suggests that travel to less-restrictive states may threaten the effectiveness of firearm laws within California. When a less-restrictive is next to a state that is more restrictive, there may be spillover effects,” Matthay said. “More research is needed to know for certain.”