Total deaths in U.S. mass shootings from 1982 to 2021, shaded to indicate the beginning and end of the Federal Assault Weapons Ban.[1]
Locations of US mass shootings in 2015, according to Shooting Tracker.
Mass shootings are incidents involving multiple victims of firearm-related violence. The precise inclusion criteria are disputed, and there is no broadly accepted definition.[2][3][4] One definition is an act of public firearm violence—excluding gang killings, domestic violence, or terrorist acts sponsored by an organization—in which a shooter kills at least four victims. Using this definition, one study found that nearly one-third of the world's public mass shootings between 1966 and 2012 (90 of 292 incidents) occurred in the United States.[5][6] Using a similar definition, The Washington Post records 163 mass shootings in the United States between 1967 and June 2019.[7]
Gun Violence Archive, frequently cited by the press, defines a mass shooting as firearm violence resulting in at least four people being shot at roughly the same time and location, excluding the perpetrator.[8][9]Using this definition, there have been 2,128 mass shootings since 2013, roughly .62[original research?] per day.[8][10][failed verification][timeframe?]
There is no fixed definition of a mass shooting in the United States.[4][16] The Investigative Assistance for Violent Crimes Act of 2012, signed into law in January 2013, defines a mass killing as one resulting in at least three victims, excluding the perpetrator.[4][17][18][19] In 2015, the Congressional Research Service (CRS), while not defining a mass shooting, does define a public mass shooting—for the purposes of its report entitled "Mass Murder with Firearms"—as "a multiple homicide incident in which four or more victims are murdered with firearms, within one event, and in one or more locations in close proximity". The CRS further states that its report "attempts to refine the relatively broad concept of mass shooting... into a narrower formulation: public mass shootings."[20] A broader definition, as used by the Gun Violence Archive, is that of "four or more shot or killed, not including the shooter".[21] The latter definition is often used by the media, press, and non-profit organizations.[22][23][24][25][26]
Some studies indicate that the rate at which public mass shootings occur has tripled since 2011. Between 1982 and 2011, a mass shooting occurred roughly once every 200 days. However, between 2011 and 2014, that rate has accelerated greatly with at least one mass shooting occurring every 64 days in the United States.[30]
There has been an approximately 50% decrease in firearm homicides in the nation overall since 1993.[when?] The decrease in firearm homicides has been attributed to better policing, a better economy and environmental factors such as the removal of lead from gasoline.[31][needs update]
Under the definition used by the Gun Violence Archive, by the end of 2019, there were 417 mass shootings; by the end of 2020, there had been 611; and by the end of 2021, 693.[32] By mid-May 2021 there were 10 mass shootings a week on average; by mid-May 2022, there was a total of 198 mass shootings in the first 19 weeks of the year, which represents 11 mass shootings a week.[33] Under the stricter definition of three or more people murdered in one event used by law-enforcement and crime-tracking organizations,[34][35] there were ten mass shootings in 2019, two in 2020, and six in 2021.[36]
Differing sources
A comprehensive report by USA Today tracked all mass killings from 2006 through 2017 in which the perpetrator willfully killed four or more people. For mass killings by firearm for instance, it found 271 incidents with a total of 1,358 victims.[37]Mother Jones listed seven mass shootings, defined as indiscriminate rampages in public places resulting in four or more victims killed,[38] in the U.S. for 2015.[39] An analysis by Michael Bloomberg's gun violence prevention group, Everytown for Gun Safety, identified 110 mass shootings, defined as shootings in which at least four people were murdered with a firearm, between January 2009 and July 2014; at least 57% were related to domestic or family violence.[40][41]
Other media outlets have reported that hundreds of mass shootings take place in the United States in a single calendar year, citing a crowd-funded website known as Shooting Tracker which defines a mass shooting as having four or more people injured or killed.[24] In December 2015, The Washington Post reported that there had been 355 mass shootings in the United States so far that year.[42] In August 2015, The Washington Post reported that the United States was averaging one mass shooting per day.[43] An earlier report had indicated that in 2015 alone, there had been 294 mass shootings that killed or injured 1,464 people.[44]Shooting Tracker and Mass Shooting Tracker, the two sites that the media have been citing, have been criticized for using a broader criteria—counting four victims injured as a mass shooting—thus producing much higher figures.[45][46]
Mass shootings tend to occur in clusters. When one occurs another is likely to follow, according to research by the Violence Project.[47]
Demographics
According to The New York Times, almost all of the mass shooting perpetrators they have published stories about are male, most commonly white men.[48] However, according to most analyses and studies, the proportion of mass shooters in the United States who are white is slightly less than the overall proportion of white people in the general population of the US.[49][50] The proportion of male mass shooters is considerably larger than the proportion of males in the general population.[50] According to the Associated Press, white men comprise nearly 50 percent of all mass shooters in the US.[51] According to the Center for Inquiry, mass shootings of family members (the most common) are usually carried out by White, middle-aged males. Felony mass shootings (connected with a previous crime) tend to be committed by young Black or Hispanic males with extensive criminal records, typically against people of the same ethnic group. Public mass shootings of persons unrelated to the shooter, and for a reason not connected with a previous crime (the rarest but most publicized) are committed by men whose racial distribution closely matches that of the nation as a whole.[52][53] Other than gender, the demographic profiles of public mass shooters are too varied to draw firm conclusions.[52]
Several possible factors may work together to create a fertile environment for mass murder in the United States according to a 2017 L.A. Times article.[54] Most commonly suggested include:
Higher accessibility and ownership of guns.[5][13][54] The US has the highest per-capita gun ownership in the world with 120.5 firearms per 100 people; the second highest is Yemen with 52.8 firearms per 100 people.[54]
Mental illness[55] and its treatment (or the lack thereof) with psychiatric drugs.[56] This is controversial.[57][58][59][60] Many of the mass shooters in the U.S. suffered from mental illness, but as of the mid 2010s[update] the estimated number of mental illness cases has not increased as significantly as the number of mass shootings.[5][attribution needed]
The desire to seek revenge for a long history of being bullied at school and/or at the workplace. In recent years[when?], perpetrators calling themselves "targeted individuals" have cited adult bullying campaigns as a reason for their deadly violence.[61][verification needed]
Desire for fame and notoriety.[54][5] Also, mass shooters learn from one another through "media contagion," that is, "the mass media coverage of them and the proliferation of social media sites that tend to glorify the shooters and downplay the victims."[when?][65][66][needs update]
Failure of government background checks due to incomplete databases and/or staff shortages.[67][68]
A panel of mental health and law enforcement experts has estimated that roughly one-third of acts of mass violence—defined as crimes in which four or more people were killed—since the 1990s were committed by people with a "serious mental illness" (SMI). However, the study emphasized that people with an SMI are responsible for less than 4% of all the violent acts committed in the United States.[69]
Survey coauthor psychiatrist Paul S. Appelbaum argued that the data from the survey indicated that "difficulty coping with life events seem more useful foci for prevention [of mass shootings] and policy than an emphasis on serious mental illness",[73] while psychiatrist Ronald W. Pies has suggested that psychopathology should be understood as a three-gradation continuum of mental, behavioral and emotional disturbance with most mass shooters falling into a middle category of "persistent emotional disturbance".[74] In 2014, the Federal Bureau of Investigation conducted a survey of 160 active shooter cases in 40 states and the District of Columbia between 2000 and 2013 (averaging approximately 11 cases annually) that found that 112 incidents (70%) took place in a business, commercial, or educational environment, 96 incidents (60%) ended before police arrived, in 64 incidents (40%) the shooter committed suicide and 64 also qualified as mass murder, while in only 6 incidents (4%) was the perpetrator female and in only 2 incidents (1%) was there more than one perpetrator.[75]
In 2015, psychiatrists James L. Knoll and George D. Annas noted that the tendency of most media attention following mass shootings on mental health leads to sociocultural factors being comparatively overlooked.[76] Instead, Knoll and Annas cite research by social psychologists Jean Twenge and W. Keith Campbell on narcissism and social rejection in the personal histories of mass shooters, as well as cognitive scientist Steven Pinker's suggestion in The Better Angels of Our Nature (2011) that further reductions in human violence may be dependent upon reducing human narcissism.[77][78] In 2018, the FBI Behavioral Analysis Unit released a survey of 63 active shooter cases between 2000 and 2013 that found that while 62 percent of active shooters showed symptoms of mental health disorders, those symptoms may have been "transient manifestations of behaviors and moods that would not be sufficient to warrant a formal diagnosis of mental illness", and only one-fourth of active shooters surveyed had a formal diagnosis of any mental health disorder (and a psychotic disorder in only 3 cases). The survey concludes that given the high lifetime prevalence of the symptoms of mental illness among the U.S. population, "formally diagnosed mental illness is not a very specific predictor of violence of any type, let alone targeted violence."[79][80]
According to a 2021 article in the journal, Injury Epidemiology, from 2014 to 2019, 59.1% of mass shootings were related to domestic violence (DV). The shooter either killed a family member or had a DV history in 68.2% of mass shootings.[81]
Weapons used
Several types of guns have been used in mass shootings in the United States. A 2014 study conducted by Dr. James Fox of 142 shootings found that 88 (62%) were committed with handguns of all types; 68 (48%) with semi-automatic handguns, 20 (14%) with revolvers, 35 (25%) with semi-automatic rifles, and 19 (13%) with shotguns.[82][83] The study was conducted using the Mother Jones database of mass shootings from 1982 to 2018.[84]High capacity magazines were used in approximately half of mass shootings.[85] Semi-automatic rifles have been used in six of the ten deadliest mass shooting events.[86][87]
Effects
Political
A British Journal of Political Science study first published in 2017 (and in print in 2019) found that increase in proximity to mass public shootings in the U.S. was associated with statistically significant and "substantively meaningful" increases in support for stricter gun control laws.[88] The study also found that repeated events, magnitude, and recency of mass shootings play a role, with "proximity to repeated events, more horrific events and more recent events" increasing "the salience of gun violence, and thus ... support for gun control."[88] However, the study found that the "most powerful effects" in support or opposition to gun control "are driven by variables related to local culture, with pronounced but expected differences emerging between respondents in rural, conservative and gun-heavy areas and those residing in urban, liberal areas with few firearm stores."[88] A separate 2019 replication study, extending the earlier panel analysis, found no evidence that mass shootings caused a "significant or substantively meaningful main effect" on attitudes toward gun control.[89] However, the study did find evidence that mass shootings "have polarizing effects conditional on partisanship": "That is, Democrats who live near a mass shooting even tend to become more supportive of gun control restrictions, while Republican attitudes shift in the opposite direction."[89] The study authors concluded, "To the extent that mass shootings may affect public opinion, the result is polarizing rather than consensus building."[89]
A 2020 study published in the American Political Science Review using data on school shootings from 2006 to 2018 concluded the incidents had "little to no effect on electoral outcomes in the United States",[90] whereas a 2021 study in the same journal, covering a broader time period (1980–2016) found that the vote share of the Democratic Party increased by an average of almost 5 percentage points in counties that had experienced a "rampage-style" school shooting.[91] Both studies found no increase in voter turnout.[90][91]
A 2021 study published in PNAS concluded that "mass shootings have a strong impact on the emotions of individuals, but the impact is politicized, limited to individuals living within the town or city where the incident occurs, and fades within a week of the incident."[92] The study authors suggested that this phenomenon could help explain why mass shootings in the U.S. have not led to meaningful policy reform efforts.[92]
Public health
A review article first published online in 2015 and then printed in January 2017 in the journal Trauma, Violence, & Abuse, concluded that "mass shootings are associated with a variety of adverse psychological outcomes in survivors and members of affected communities" and that while "the psychological effects of mass shootings on indirectly exposed populations" is less well-understood, "there is evidence that such events lead to at least short-term increases in fears and declines in perceived safety."[93] Identified risk factors for adverse psychological outcomes have included, among others, demographics, greater proximity to the attack, acquaintance with victims, and less access to psychosocial resources.[93]
The following mass shootings are the deadliest to have occurred in modern U.S. history. Only incidents with ten or more fatalities, excluding those of the perpetrators, are included. This list starts in 1949, the year in which Howard Unruh committed his shooting, which was the first in modern U.S. history to incur ten or more fatalities.[94]
^Bjelopera, Jerome (March 18, 2013). "Public Mass Shootings in the United States"(PDF). Congressional Research Service. Archived from the original(PDF) on September 9, 2013. Retrieved August 26, 2018. There is no broadly agreed-to, specific conceptualization of this issue, so this report uses its own definition for public mass shootings.
^ abcGreenberg, Jon; Jacobson, Louis; Valverde, Miriam (February 14, 2018). "What we know about mass shootings". PolitiFact. Tampa Bay Times. Retrieved February 20, 2018. As noted above, there is no widely accepted definition of mass shootings. People use either broad or restrictive definitions of mass shootings to reinforce their stance on gun control. After the 2012 Sandy Hook school shooting, Congress defined "mass killings" as three or more homicides in a single incident. The definition was intended to clarify when the U.S. Attorney General could assist state and local authorities in investigations of violent acts and shootings in places of public use.
^Cherney, Elyssa (August 5, 2019). "The Same Weekend as Massacres in El Paso and Dayton, 15 People Were Shot in 2 Chicago Incidents. Why Aren't Those Called Mass Shootings Too?". Chicago Tribune. Retrieved August 7, 2019. Different organizations use a variety of measures to determine whether an act of gun violence meets the criteria of a mass shooting.... How you define the term results in vastly different counts: The Gun Violence Archive has tallied 255 mass shootings in 2019 so far, while Mother Jones lists the number at seven. Some databases also exclude gang-related or domestic shootings.... Researchers on both sides of the spectrum say that data about mass shootings can be misleading if not presented with a clear methodology.
^Ingraham, Christopher (December 3, 2015). "What makes a 'mass shooting' in America". Washington Post. Retrieved November 5, 2017. But starting in 2013, federal statutes defined "mass killing" as three or more people killed, regardless of weapons.
^Follman, Mark. "What Exactly Is A Mass Shooting". Mother Jones. Retrieved August 9, 2015. In January 2013, a mandate for federal investigation of mass shootings authorized by President Barack Obama lowered that baseline to three or more victims killed.
^Victor, Daniel (February 17, 2018). "Mass Shooters Are All Different. Except for One Thing: Most Are Men". The New York Times. Retrieved April 10, 2018. About the only thing almost all of them have in common is that they are men. [...] Examining past New York Times coverage of mass shootings reveals some shared tendencies of the gunmen, including the fact that they are most commonly white
^ abEngber, Daniel (October 6, 2017). "What the White Mass-Shooter Myth Gets Right and Wrong About Killers' Demographics". Slate Magazine. Retrieved August 4, 2019. roughly 70 percent of the shooters in mass killings were white—certainly a majority. But according to Census Bureau estimates for 2012, whites accounted for 73.9 percent of all Americans" "men are even more overrepresented among mass shooters and mass killers than they are among “normal” killers
^"Mass shootings so far this year almost reach 2018 levels". AP NEWS. August 8, 2019. Retrieved March 26, 2021. The AP/USA Today/Northeastern database shows that many mass shootings are committed by a certain demographic: young, white men. Most mass shootings in the U.S. are carried out by men, with white men making up nearly 50 percent of the shooters, the database shows.
^ abRadford, Benjamin (May 31, 2019). "Who Are Mass Shooters? Mass Shooter Demographics". Center for Inquiry. Retrieved March 30, 2021. The topic of mass shootings is fraught not only with political agendas but also with rampant misinformation. Facile comparisons and snarky memes dominate social media, crowding out objective, evidence-based evidence and analysis. This is effective for scoring political points but wholly counterproductive for understanding the nature of the problem and its broader issues.
^Burgess, Ann Wolbert; Garbarino, Christina; Carlson, Mary I. (2006). "Pathological teasing and bullying turned deadly: Shooters and suicide". Victims and Offenders. 1 (1): 1–14. doi:10.1080/15564880500498705. S2CID144987837.
^Fisher, Marc (February 15, 2018). "The AR-15: 'America's rifle' or illegitimate killing machine?". The Washington Post. Retrieved May 11, 2018. ...high-capacity magazines have been used in more than half of mass shootings over four decades, according to several studies.
^Berger, Meyer (September 7, 1949). "Veteran Kills 12 in Mad Rampage on Camden Street". The New York Times. Retrieved July 6, 2018. Howard B. Unruh, 28 years old, a mild, soft-spoken veteran of many armored artillery battles in Italy, France, Austria, Belgium and Germany, killed twelve persons with a war souvenir Luger pistol in his home block in East Camden this morning. He wounded four others.
^513 Pa. 318 (Supreme Court of Pennsylvania 1987) ("In the space of about one hour, appellant shot fourteen people with a Colt AR-15 semi-automatic rifle, killing thirteen and wounding one.").