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Mass shootings in the United States

Total deaths in US mass shootings.[1]
Locations of US mass shootings in 2015, according to Shooting Tracker.

There is no fixed definition of a mass shooting,[2] but a common definition is an act of violence—excluding gang killings, domestic violence, or terrorist acts sponsored by an organization—in which a gunman 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.[3][4] Using the same definition, Gun Violence Archive (external link) records 152 mass shootings in the United States between 1967 and May 2018, averaging eight fatalities per incident when the perpetrator's death is included.[5]

The United States has had more mass shootings than any other country.[6][3][7][8][9] Shooters generally either die by suicide afterwards or are restrained or killed by law enforcement officers or civilians.[10]



There is no fixed definition of a mass shooting in the United States.[2] The Investigative Assistance for Violent Crimes Act of 2012, signed into law by Congress in January 2013, defines a "mass killing" as one resulting in at least 3 victims, excluding the perpetrator.[11][2][12][13] In 2015, the Congressional Research Service defined a mass shooting 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".[14] A broader definition, as used by the Gun Violence Archive, is that of "4 or more shot or killed, not including the shooter".[15] This definition, of four people shot regardless of whether or not that results in injury or death, is often used by the press and non-profit organizations.[16][17][18][19][20]


Memorial at the Welcome to Fabulous Las Vegas sign following the 2017 Las Vegas shooting, which resulted in 59 deaths and 851 non-fatal injuries.

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.[21]

In recent years, the number of public mass shootings has increased substantially, although there has been an approximately 50% decrease in firearm homicides in the nation overall since 1993. 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.[22]

Differing sourcesEdit

A comprehensive report by USA Today tracked all mass killings from 2006 through 2017 in which the perpetrator willfully killed 4 or more people. For mass killings by firearm for instance, it found 271 incidents with a total of 1,358 victims.[23] Mother Jones listed seven mass shootings, defined as indiscriminate rampages in public places resulting in four or more victims killed,[24] in the U.S. for 2015.[25] 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.[26][27]

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.[18] In December 2015, The Washington Post reported that there had been 355 mass shootings in the United States so far that year.[28] In August 2015, The Washington Post reported that the United States was averaging one mass shooting per day.[29] An earlier report had indicated that in 2015 alone, there had been 294 mass shootings that killed or injured 1,464 people.[30] 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.[31][32]


The majority of perpetrators are white males who act alone.[33] However, on a per capita basis perpetrators of mass shootings are not disproportionately Caucasian. [34]

Contributing factorsEdit

Several possible factors may work together to create a fertile environment for mass murder in the United States.[35] Most commonly suggested include:

  1. Higher accessibility and ownership of guns.[35][3][8] 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.[35]
  2. Mental illness[36] and its treatment (or the lack thereof) with psychiatric drugs.[37] This is controversial.[38][39] Many of the mass shooters in the U.S. suffered from mental illness, but the estimated number of mental illness cases has not increased as significantly as the number of mass shootings.[3] Under 5% of violent behaviors in the U.S. are committed by persons with mental health diagnoses.[40]
  3. The desire to seek revenge for a long history of being bullied at school.[41]
  4. The widespread chronic gap between people's expectations for themselves and their actual achievement,[35] and individualistic culture.[42]
  5. Desire for fame and notoriety.[35][3] 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".[43]
  6. The copycat phenomenon.[3]
  7. Failure of government background checks due to incomplete databases and/or staff shortages.[44][45]

Weapons usedEdit

Several types of guns have been used in mass shootings in the United States, including rifles, handguns, and shotguns. A 2014 study of 142 shootings by Dr. James Fox found 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.[46][47][48] The study was conducted using the Mother Jones database of mass shootings from 1982–2018.[49] High capacity magazines were used in approximately half of mass shootings.[50] Semi-automatic rifles such as the AR-15 or similar have been used in six of the ten deadliest mass shooting events.[51][52]

Deadliest mass shootings since 1949Edit

The following mass shootings are the deadliest to have occurred in modern U.S. history (1949 to present). Only incidents with ten or more victim fatalities are included.[53]

  Was previously the deadliest mass shooting
Incident Year Deaths Injuries Type of firearm(s) used Ref(s)
1 Las Vegas shooting 2017 58 (plus 1 perp.) 851 (422 from gunfire) Semi-automatic rifles and revolver [54][55]
2 Orlando nightclub shooting   2016 49 (plus 1 perp.) 53 Semi-automatic rifle and pistol [54][55]
3 Virginia Tech shooting   2007 32 (plus 1 perp.) 23 Semi-automatic pistols [54]
4 Sandy Hook Elementary School shooting 2012 27 (plus 1 perp.) 2 Semi-automatic rifle and pistol [54]
5 Sutherland Springs church shooting 2017 26 (plus 1 perp.)[fn 1] 20 Semi-automatic rifle [56][55]
6 Luby's shooting   1991 23 (plus 1 perp.) 27 Semi-automatic pistols [54]
7 San Ysidro McDonald's massacre   1984 21 (plus 1 perp.) 19 Semi-automatic rifle, pistol, and shotgun [54]
8 University of Texas tower shooting   1966 17 (plus 1 perp.)[fn 1] 31 Rifles, revolver, pistols, and shotgun [54]
Stoneman Douglas High School shooting 2018 17 17 Semi-automatic rifle [57]
10 Edmond post office shooting 1986 14 (plus 1 perp.) 6 Semi-automatic pistols [54]
San Bernardino attack 2015 14 (plus 2 perps.) 24 Semi-automatic rifles [54][55]
12 Fort Hood shooting 2009 14 [fn 1] 32 (plus 1 perp.) Semi-automatic pistol and revolver [58][59]
13 Columbine High School massacre 1999 13 (plus 2 perps.) 24 Semi-automatic carbine, semi-automatic pistol, shotguns [60]
Binghamton shootings 2009 13 (plus 1 perp.) 4 Semi-automatic pistols [61]
15 Camden shootings   1949 13 3 Semi-automatic pistol [62][63]
Wilkes-Barre shootings 1982 13 1 Semi-automatic rifle [64][65][66]
Wah Mee massacre 1983 13 1 Semi-automatic pistol(s) and/or revolver(s)[fn 2] [67]
18 Aurora shooting 2012 12 70 Semi-automatic rifle, pistol, and shotgun [68][55][69]
Washington Navy Yard shooting 2013 12 (plus 1 perp.) 8 Semi-automatic pistol and shotgun [70][71]
Thousand Oaks shooting 2018 12 (plus 1 perp.) 25 Semi-automatic pistol [72][73]
21 Easter Sunday massacre 1975 11 0 Semi-automatic pistols and revolver [74]
Pittsburgh synagogue shooting 2018 11 6 (plus 1 perp.) Semi-automatic rifle, semi-automatic pistols [75]
23 Palm Sunday massacre 1984 10 0 Semi-automatic pistols [76]
Geneva County massacre 2009 10 (plus 1 perp.) 6 Semi-automatic rifles, revolver, and shotgun [77][78]
Santa Fe High School shooting 2018 10 14 Shotgun and revolver [79]

See alsoEdit


  1. ^ a b c The fatality total includes an unborn child.
  2. ^ During the massacre, the perpetrators used three .22 caliber handguns of an unknown type which were never recovered by the authorities.


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