Priscilla Olivas, 19, of Las Vegas, lights a candle Tuesday at a street vigil along the Las Vegas Strip. (Salwan Georges/The Washington Post)

The deadly mass public shooting in Las Vegas has reignited the debate about regulating firearms. Advocates of gun rights say that “the only thing that stops a bad guy with a gun is a good guy with a gun,” while gun control activists argue that “there’s a disconnect between what the American public wants on this issue and what [our] elected officials are doing about it.” And some will wonder whether mass shootings have any effect on public opinion.

They do — but in a very specific way. In our research, we discovered that people who live close to a mass shooting are more likely to support gun control than those who don’t.

On average, support for gun regulation has dropped over the past 25 years.

Years of polling data about Americans’ attitudes toward gun legislation show that — at least in the aggregate — American support for gun regulation has dropped over the past 25 years. In the 1990s, more than 6 out of 10 people favored firearm restrictions. But by the late 2000s, less than half of those surveyed supported gun regulation. Support does spike when there are highly publicized mass shootings, like those in Columbine, Colo., and Newtown, Conn. However, these spikes quickly fall back to the pattern of decline. Overall, even though U.S. mass shootings have increased, American support for gun legislation has declined. Today, only 51 percent support legislation to restrict gun ownership.

These polling results miss important geographic differences in attitudes. The closer you live to the site of a mass shooting, the more likely you are to feel threatened by gun violence — and the more you support regulating firearms.

Here’s how we did our research:

We first identified all known mass public shootings by reviewing the Stanford Geospatial Center’s “Mass Shootings in America” project, USA Today’s “Behind the Bloodshed” mass killing database, and Mother Jones’ “A Guide to Mass Shootings in America.” We combined results from these databases, discarding duplicates and keeping only cases in which three or more members of the general public were injured or killed with a firearm, leaving out targeted murders like family, acquaintance and drug or gang-related killings. This data set allows us to consider incidents where a shooter opened fire in a public place (e.g., school, shopping mall, movie theater, church, etc.) targeting seemingly random members of the public.

From 1966 to 2015, our database contains 210 mass public shootings. Most occurred after 2007, when the Virginia Tech shooting was in the news. Two-thirds occurred after the Columbine shooting in 1999. Mass shootings appear to be increasing over time.

The average number killed in these attacks was 4.5 people; the average number not killed but injured by gunshot was five. Before the Las Vegas shooting, the largest number killed was 49, at the Pulse nightclub in Orlando in 2016 (although because our data set goes only to 2015, our published research shows it as 33 at Virginia Tech); the largest number injured by gunshot was 58 at the Aurora, Colo., theater shooting in 2012. The figure below shows a map of this data, which marks each event’s location and varies the size of the markers according to the number of people injured or killed.


Locations of mass public shootings in the continental United States, 1966—2015

So how did these mass shootings affect local and regional opinion toward gun regulation? To find out, we paired this shooting data with several large and respected public opinion surveys that measured respondents’ gun policy preferences: the 2010 Cooperative Congressional Election Study (CCES), the 2010-2012 CCES Panel Study, and the 2010 Pew Political Independents Survey. This data not only measures respondents’ opinions about government regulation of firearms, but also includes essential control variables. The geocoded data also enabled us to locate respondents spatially so that we could test whether reported preferences for gun control are related to how close respondents lived to mass public shootings.

In all three surveys, living closer to a mass shooting did indeed make a difference, increasing respondents’ support for stricter firearms regulation.

What’s especially interesting is that increased support doesn’t vary by party. Rather, support for regulation increases depending on how many mass shootings have happened near you; how many people were killed; and how recently they occurred.

Our analysis includes controls for relevant demographic factors (e.g., respondents’ race, sex, age and so on) and contextual variables (e.g., population density, number of firearm stores per capita, etc.) that might influence both the location of mass shooting events and respondents’ attitudes toward gun control policy.

Smaller countries pass laws soon after mass shootings. 

In other Western nations, after mass shootings, governments quickly pass new gun laws. For example, after the 1996 Dunblane Massacre of 16 British schoolchildren and one teacher, the United Kingdom passed two firearms acts and a permanent ban on private handgun ownership. Similarly, after the 1996 Port Arthur Massacre in Tasmania left 35 dead and 23 wounded, the Australian government introduced the National Firearms Agreement, which outlawed automatic and semiautomatic weapons and pump-action shotguns.

That hasn’t happened in the United States. We think it is not because the public fails to respond. Our research suggests a clear link between those who have lived near a mass shooting and a desire for stricter gun regulation. But most Western countries are smaller — both geographically and in population — than the United States. The nation may not pass gun legislation until there have been enough mass shootings that most Americans feel personally touched by the possibility of being shot at random.

Benjamin J. Newman is associate professor of public policy and political science at the University of California at Riverside. His research focuses on race and ethnic politics, class and income inequality, and urban politics and policy.

Todd K. Hartman is lecturer in quantitative social science at the Sheffield Methods Institute and a statistical ambassador for the Royal Statistical Society. Find him on Twitter @tkhartman.