THIS DATASET WAS LAST UPDATED AT 8:11 PM EASTERN ON JULY 30

OVERVIEW

2019 had the most mass killings since at least the 1970s, according to the Associated Press/USA TODAY/Northeastern University Mass Killings Database.

In all, there were 45 mass killings, defined as when four or more people are killed excluding the perpetrator. Of those, 33 were mass shootings . This summer was especially violent, with three high-profile public mass shootings occurring in the span of just four weeks, leaving 38 killed and 66 injured.

A total of 229 people died in mass killings in 2019.

The AP's analysis found that more than 50% of the incidents were family annihilations, which is similar to prior years. Although they are far less common, the 9 public mass shootings during the year were the most deadly type of mass murder, resulting in 73 people's deaths, not including the assailants.

One-third of the offenders died at the scene of the killing or soon after, half from suicides.

About this Dataset

The Associated Press/USA TODAY/Northeastern University Mass Killings database tracks all U.S. homicides since 2006 involving four or more people killed (not including the offender) over a short period of time (24 hours) regardless of weapon, location, victim-offender relationship or motive. The database includes information on these and other characteristics concerning the incidents, offenders, and victims.

The AP/USA TODAY/Northeastern database represents the most complete tracking of mass murders by the above definition currently available. Other efforts, such as the Gun Violence Archive or Everytown for Gun Safety may include events that do not meet our criteria, but a review of these sites and others indicates that this database contains every event that matches the definition, including some not tracked by other organizations.

This data will be updated periodically and can be used as an ongoing resource to help cover these events.

Using this Dataset

To get basic counts of incidents of mass killings and mass shootings by year nationwide, use these queries:

Mass killings by year

Mass shootings by year

To get these counts just for your state:

Filter killings by state

Definition of "mass murder"

Mass murder is defined as the intentional killing of four or more victims by any means within a 24-hour period, excluding the deaths of unborn children and the offender(s). The standard of four or more dead was initially set by the FBI.

This definition does not exclude cases based on method (e.g., shootings only), type or motivation (e.g., public only), victim-offender relationship (e.g., strangers only), or number of locations (e.g., one). The time frame of 24 hours was chosen to eliminate conflation with spree killers, who kill multiple victims in quick succession in different locations or incidents, and to satisfy the traditional requirement of occurring in a “single incident.”

Offenders who commit mass murder during a spree (before or after committing additional homicides) are included in the database, and all victims within seven days of the mass murder are included in the victim count. Negligent homicides related to driving under the influence or accidental fires are excluded due to the lack of offender intent. Only incidents occurring within the 50 states and Washington D.C. are considered.

Methodology

Project researchers first identified potential incidents using the Federal Bureau of Investigation’s Supplementary Homicide Reports (SHR). Homicide incidents in the SHR were flagged as potential mass murder cases if four or more victims were reported on the same record, and the type of death was murder or non-negligent manslaughter.

Cases were subsequently verified utilizing media accounts, court documents, academic journal articles, books, and local law enforcement records obtained through Freedom of Information Act (FOIA) requests. Each data point was corroborated by multiple sources, which were compiled into a single document to assess the quality of information.

In case(s) of contradiction among sources, official law enforcement or court records were used, when available, followed by the most recent media or academic source.

Case information was subsequently compared with every other known mass murder database to ensure reliability and validity. Incidents listed in the SHR that could not be independently verified were excluded from the database.

Project researchers also conducted extensive searches for incidents not reported in the SHR during the time period, utilizing internet search engines, Lexis-Nexis, and Newspapers.com. Search terms include: [number] dead, [number] killed, [number] slain, [number] murdered, [number] homicide, mass murder, mass shooting, massacre, rampage, family killing, familicide, and arson murder. Offender, victim, and location names were also directly searched when available.

This project started at USA TODAY in 2012.

Contacts

Contact AP Data Editor Justin Myers with questions, suggestions or comments about this dataset at jmyers@ap.org. The Northeastern University researcher working with AP and USA TODAY is Professor James Alan Fox, who can be reached at j.fox@northeastern.edu or 617-416-4400.

There were public mass shootings in the United States in every year between 1998 and 2019, resulting in a total of almost 1,900 casualties. When compared with the number of victims of mass shootings in all other developed nations (based on UN specifications), the United States' figure is often higher than all of these countries combined. There were notable exceptions, such as the attacks in Paris on the evening of November 13. 2015, which resulted in 130 deaths and 416 injuries (the same year the Charlie Hebdo shooting killed 12 people and injured 11 more), the 2011 attacks in Oslo and Utøya, Norway and Liège, Belgium which had a combined casualty count of 240 due to gunfire. In the United States, the deadliest mass shooting in this time was the Las Vegas Strip massacre in 2017.

The deadliest school shooting in the United States as of September 4, 2024, was the Virginia Tech massacre, with 32 fatalities and 23 injuries. The next deadliest school shooting (based on fatalities) was the Sandy Hook Elementary massacre in Newtown, Connecticut, with 27 fatalities. School shootings in the U.S. Mass shootings in the United States have become a disturbingly common occurrence, and sadly, so have school shootings. The Columbine school shooting is perhaps the most famous in the country’s history, and since 1999 (when the shooting occurred), the number of school shootings has only increased. Many measures have been used to try to prevent school shootings, including security guards and metal detectors being deployed in schools, and even the suggestion that teachers be allowed to carry guns in schools. Gun control Gun control in the United States is a sticky issue, since gun ownership is enshrined in the Constitution. Some advocate for stricter gun control laws to try to prevent future mass shootings, while others say that this is unconstitutional. Gun ownership rates in the U.S. are high, with the share of American households owning at least one firearm remaining relatively steady since 1972.

As of March 19, ***** school shootings were recorded in the United States in 2025, impacting K-12 school grounds and college campuses nationwide. In comparison, there were ** school shooting incidents recorded in 2024. In addition to schools, gun-related violence occurs in many public places within the United States, including workplaces, churches, restaurants, and nightclubs. The source defines school shootings as incidents of gun violence which occurred on school property and at least one person was shot, not including the shooter. School property includes, but is not limited to, buildings, fields, parking lots, stadiums and buses. Accidental discharges of firearms are included, as long as at least one person is shot, but not if the sole shooter is law enforcement or school security.

As of July 14, 2025, there have been a total of 277 school shootings in California since 1966, the most out of any state. Texas had the second highest number of school shootings within this time period, with 237 shootings. The source defines a school shooting as every time a gun is brandished, fired, or a bullet hits school property for any reason, regardless of the number of victims (including zero), time, day or the week, or reason, including gang shootings, domestic violence, shootings at sports games and after hours school events, suicides, fights that escalate into shootings, and accidents.

Between 1982 and September 2024, 82 out of the 151 mass shootings in the United States were carried out by White shooters. By comparison, the perpetrator was African American in 26 mass shootings, and Latino in 12. When calculated as percentages, this amounts to 54 percent, 17 percent, and eight percent respectively. Race of mass shooters reflects the U.S. population Broadly speaking, the racial distribution of mass shootings mirrors the racial distribution of the U.S. population as a whole. While a superficial comparison of the statistics seems to suggest African American shooters are over-represented and Latino shooters underrepresented, the fact that the shooter’s race is unclear in around nine percent of cases, along with the different time frames over which these statistics are calculated, means no such conclusions should be drawn. Conversely, looking at the mass shootings in the United States by gender clearly demonstrates that the majority of mass shootings are carried out by men. Mass shootings and mental health With no clear patterns between the socio-economic or cultural background of mass shooters, increasing attention has been placed on mental health. Analysis of the factors Americans considered to be to blame for mass shootings showed 80 percent of people felt the inability of the mental health system to recognize those who pose a danger to others was a significant factor. This concern is not without merit – in over half of the mass shootings since 1982, the shooter showed prior signs of mental health issues, suggesting improved mental health services may help deal with this horrific problem. Mass shootings and guns In the wake of multiple mass shootings, critics have sought to look beyond the issues of shooter identification and their influences by focusing on their access to guns. The majority of mass shootings in the U.S. involve firearms which were obtained legally, reflecting the easy ability of Americans to purchase and carry deadly weapons in public. Gun control takes on a particular significance when the uniquely American phenomenon of school shootings is considered. The annual number of incidents involving firearms at K-12 schools in the U.S. was over 100 in each year since 2018. Conversely, similar incidents in other developed countries exceptionally rare, with only five school shootings in G7 countries other than the U.S. between 2009 and 2018.

As of September 2024, California had the most mass shootings in the United States, with 26 total shootings since 1982. The source defines a mass shooting as a shooting where three or more people were killed. Recently, a mass shooting occurred in the state of Maine on October 26, 2023, during which one of the highest number of fatalities from a mass shooting was recorded after Robert Card opened fire in a bowling alley and a bar, killing 18 and injuring 13 others. Firearms in the U.S. Mass shootings in the United States are disturbingly common. In comparison with other Western countries, there are significantly more shootings in the U.S., which some theorize is due to the relatively lax gun control laws. Gun control laws in the U.S. are dependent on the state, and the right to own a firearm is enshrined in the United States Constitution. Mass shootings The worst mass shooting in the U.S. was the Las Vegas Strip massacre in 2017, which resulted in 58 deaths and 546 injuries. 13 of the worst mass shootings in the United States have occurred since 2015 and the vast majority of these incidents in the U.S. have been carried out by shooters who are White and male.

Handguns are the most common weapon type used in mass shootings in the United States, with a total of 167 different handguns being used in 117 incidents between 1982 and September 2024. These figures are calculated from a total of 151 reported cases over this period, meaning handguns are involved in about 78 percent of mass shootings. The involvement of semi-automatic rifles in mass shootings Owing to their use in several high-profile mass shootings, there has been much public discussion over the suitability or necessity of assault weapons for the purpose of self-defense. While any definition of assault weapon is contentious, semi-automatic rifles are generally the main focus of debates around this issue. Since 1982, there has been a known total 65 mass shootings involving rifles, mostly semi-automatics. This figure is underreported, however, as it excludes the multiple semi-automatic (and fully automatic) rifles used in the 2017 Las Vegas Strip massacre – the worst mass shooting in U.S. history, killing 58 and wounding 546. In fact, semi-automatic rifles were featured in four of the five deadliest mass shootings, being used in the Orlando nightclub massacre, Sandy Hook Elementary massacre and Texas First Baptist Church massacre. Mass shootings and gun control Despite evidence of strict gun control measures reducing the frequency and severity of mass shootings in countries like Australia, citizens in the United States remain deeply divided over the issue. According to a survey about the expected impact of gun laws on the number of mass shootings, a slim majority of Americans believe that gun control measures will have little-to-no effect. Most likely, this opinion is influenced by an underlying commitment among many in the U.S. to the greater importance of protecting gun ownership rights than limiting access to firearms. This sits in sharp contrast to many other developed countries. For example, most Canadians support a ban on civilian owned firearms.