In a respite from years with nation-wrenching mass killing incidents, the United States is on track to record the lowest level of such deadly events in two decades, according to one group of researchers tracking the data.
There have been 17 mass killings, 14 of which involved guns, recorded this year, according to a database maintained by Northeastern University, in partnership with the Associated Press and USA Today. While that number could increase in December, it is the lowest since the database was established in 2006. And it represents a significant drop from recent years – including 2023, which saw more than three dozen such incidents.
Northeastern’s database tracks incidents in which four or more people were killed intentionally, excluding the assailant, in a 24-hour period. Most mass violence is gun-related, which the chart accompanying this article focuses on. But the database also tracks other incidents of mass killing, such as stabbings or the use of vehicles to attack pedestrians.
Why We Wrote This
While the annual number of mass violence events spikes and dips, even a slight reprieve from bloodshed in a nation that sees thousands of homicides each year highlights shifts in policies.
The database offers an important perspective – but only one – on the nation’s struggles with violence, which does not always end in fatalities. Another organization, for example, the Gun Violence Archive, has counted 381 mass shootings this year, compared with 503 for all of 2024. This group defines a mass shooting as an event in which four or more people are shot, though not necessarily killed.
Some experts credit recent crime policies on both local and national levels for some of the progress – as well as stepped-up school safety measures. In part, the shift might also represent what statisticians refer to as a “reversion to the mean,” suggesting a return to more average crime levels after a spike in preceding years.
Associated Press/USA TODAY/Northeastern University Mass Killings Database, U.S. Centers for Disease Control
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Jacob Turcotte/Staff
While the long-term trend in mass killings is characterized by spikes and dips – not a clear rising or falling direction – the recent data shows a decline.
“The overall violent crime picture seems to be getting a little better in the United States,” says Adam Lankford, author of “The Myth of Martyrdom,” which identifies motivations for violent rampages.
A reprieve, but an ongoing challenge
For public officials and citizens alike, any evidence of a drop in mass violence is welcome news – a reprieve from bloodshed in a nation that sees tens of thousands of gun-involved deaths each year.
Determining what factors cause such violence to rise and fall is a challenging task, especially when attempting to draw scientific conclusions. Criminologists are still debating why homicides dropped precipitously during the 1990s.
While other violence databases also suggest a general decline in mass violence, Professor Lankford notes that the kind of premeditated public mass killings that tend to change the behavior of Americans did not decline in the new findings, with most of the shift attributed to a decline in mass killings in or near people’s homes.
What’s more, he says, a rise in targeted political killings might well deflate any sense of relief from a slowdown of mass killings.
The type of violent acts that inspire fear and motivate responses are “school shootings, shootings at malls, movie theaters,” says Professor Lankford, who is also a criminologist at the University of Alabama. That means “that the type of mass killing that has decreased most significantly is not the type of mass killing that Americans appear to be most afraid of.”
Still, one of those categories has seen a big recent drop.
In years past, some of the nation’s most tragic mass shootings have occurred at schools – including Sandy Hook Elementary in Newtown, Connecticut; Robb Elementary in Uvalde, Texas; and Marjory Stoneman Douglas High School in Parkland, Florida.
Melanie Stetson Freeman/Staff/File
So far this year, no act rising to the mass killing definition has taken place on a school campus.
Part of that shift might be the result of changes in school policy and practice.
Twenty-two states, for example, now mandate the establishment of school threat-assessment teams, and the 2022 Safer Communities Act included millions of federal dollars to support gun violence prevention programs.
“You can make the case that we’re seeing more threats but not as many attacks as schools have implemented threat assessment programs,” says Eric Madfis, director of the Violence Prevention and Transformation Research Collaborative at the University of Washington in Tacoma.
“When I talk to people who have averted a school shooting, a big part of it is breaking through a code of silence of students reporting things,” he adds.
As part of that, “we have gone from zero tolerance policies where we punish a kid who accidentally brings a knife to school to looking at the substance and content of threats,” he continues. “Do they have the ability to carry it out, access to weapons, plans of who they are going to kill, when, and where? We’ve seen amazing outcomes” from that shift.
A return to normalcy after the COVID-19 pandemic’s whiplash might also be a contributing factor, alongside an overall decline in violent crime rates since 2022.
Renewed focus by police on tackling gun proliferation in high crime areas and making arrests in more murder cases might also be having a positive impact.
Experts say improved emergency care is also leading to fewer deaths when mass shootings do occur.
A shooting in Minnesota earlier this year, for example, didn’t reach Northeastern’s definition of a mass killing, even though about 20 people were injured. Why? Despite the enormous tragedy of the event, in which two children died, experts say the quick actions of Minneapolis responders likely saved many lives.
A matter of care
Social scientists suggest that one significant causal factor of violent crimes throughout American history has been levels of societal well-being, including political agency and expression.
Following the American Revolution, the expansion of the voting franchise, a vibrant economy based on business ownership, and a shared sense of patriotism contributed to the New England region achieving the lowest homicide rates in the Western world in the late 1700s.
Conversely, from deadly 1960s riots in several U.S. cities to instances of violence accompanying some protests after the murder of George Floyd in 2020, the prevalence of protest-related violence has been among the historical predictors of high homicide rates in the modern age.
Yet, this year, the U.S. has seen numerous protests, including large “No Kings” demonstrations, without a homicide spike. The protests have been defined not by violence but by social commentary (posters, costumes, and speeches) aimed at politicians, most notably President Donald Trump.
Partisan echo chambers might also be concealing shifts in feelings among Americans about their own prospects and those of the communities where they reside, as partisanship intensifies.
“The key to low homicide rates is successful nation-building,” writes Randolph Roth, author of “American Homicide,” in a 2024 research paper on why homicide rates rise and fall.
At the same time, stubbornly high numbers of gun deaths overall – including suicides, which are far more numerous than homicides – challenge the notion that general well-being is pushing down mass violence, at least at this moment.
Just because a society might be getting better at preventing mass shootings doesn’t mean the threat is diminishing, says Professor Lankford. He cites targeted political violence and a 2023 report from the U.S. surgeon general on an epidemic of loneliness and isolation as matters of concern.
“If anybody is interpreting this [dip in mass killings] as, ‘Congratulations, we’ve stopped school shootings or workplace shootings,’ then they’re just wrong about what the data show,” he says.
