An updated version of this graphic can be found here.

The death tolls change, the places change: 26 at a church, 26 in an elementary school, 49 in a nightclub, 58 at a country music festival. The faces in the memorial photos change every time.

But the weapons are the common denominator.

Mass killings in the United States are most often carried out with guns, usually handguns, most of them obtained legally.

There is no universally accepted definition of a mass shooting, and different organizations use different criteria. In this piece we use a narrow definition and look only at the deadliest mass shootings, beginning Aug. 1, 1966, when ex-Marine sniper Charles Whitman killed his wife and mother, then climbed a 27-story tower at the University of Texas and killed 14 more people before police shot him to death. The numbers here refer to 146 events in which four or more people were killed by a lone shooter (or two shooters in three cases). An average of eight people died during each event, often including the shooters.

[The number of ‘mass shootings’ in the U.S. depends on how you count]

This data — compiled from Mother Jones; Grant Duwe, author of “Mass Murder in the United States: A History,” and Washington Post research — does not include gang killings, shootings that began as other crimes such as robberies, and killings that involved only the shooter’s family.

1,048 victims

Each gun was used to kill an average of four people, not counting shooters. The 1,048 people came from nearly every imaginable race, religion and socioeconomic background, and 161 were children or teenagers.

Hover to read each victim's story

The youngest victim Eight-month-old Carlos Reyes was buried in a casket with his mother, Jackie, who had tried to shield him as an unemployed father of two killed 21 at a busy McDonald’s in San Ysidro, Calif., in 1984. The man told his wife he was going out “hunting humans” and opened fire with an Uzi, a shotgun and a semiautomatic pistol. In addition, two unborn children are included in official death tolls from the University of Texas tower shooting and the Sutherland Springs shooting. The oldest victim Louise De Kler, 98, still took her pool cue and boombox to the rec room at Pinelake Health and Rehab and shot pool with the “young guys,” her daughter told the Associated Press. She was shot to death on March 29, 2009, along with seven other residents and a nurse, by a man who had come to the Carthage, N.C., nursing home looking for his estranged wife.

292 guns

Shooters brought an average of four weapons to each shooting; the Las Vegas music festival shooter had 23. We don’t know how all the guns were acquired, but of the ones we know, 168 were obtained legally and 48 were obtained illegally.

Hover to learn more about each gun

AK-47 A drifter carrying a Chinese variant of an AK-47 and a semiautomatic handgun fired more than 100 rounds into an elementary school playground in Stockton, Calif., on Jan. 17, 1989, killing five children and wounding 30 other students and teachers before shooting himself. The gunman had a history of crime, mental illness and drug abuse, but he bought the guns legally in Oregon and California. Five months later, California enacted the country’s first ban on assault weapons. 9mm Shooters in some of the deadliest mass shootings in U.S. history carried models of the country’s most popular types of weapons. The gunman who killed 32 students and teachers at Virginia Tech on April 16, 2007, used a 9mm semiautomatic Glock 19 (and a .22-caliber Walther P22, another popular caliber). These guns, used by many law enforcement officers, are generally light, inexpensive, easy to conceal and require little strength to control. In this tally of weapons, 9mm semiautomatic handguns show up more than any other weapon.

149 shooters

All but three of the mass shooters were male; the vast majority were age 20 to 49. More than half — 86 of them — died at or near the scene of the shooting, often by killing themselves.

Hover to read about each shooter

An anomaly Tashfeen Malik, the 27-year-old Pakistani mother who helped kill 14 partygoers at her husband’s workplace in San Bernardino, was an anomaly among mass shooters in two ways: She was part of a pair rather than a lone gunman, and she was a woman. The other two women in this data set are Jennifer San Marco, who in 2006 killed a former neighbor and six employees at a Goleta, Calif., mail-processing facility where she once worked; and Cherie Rhoades, who killed her brother and three others at a tribal council meeting in 2014. Two middle-schoolers Andrew Golden, 11, and Mitchell Johnson, 13, pulled a fire alarm to flush students and teachers out of their Jonesboro, Ark., middle school on March 24, 1998, and began shooting, killing four girls and a teacher and wounding 10 others. Between them, they had nine guns including two semiautomatic assault pistols. Both were released from prison when they turned 21.

40 states and the District

Twenty-five percent of the mass shootings occurred in workplaces, and 1 in 8 took place at schools. Many took place in stores, restaurants and bars, or in religious or military locations. Others occurred in a wide variety of public places. California has had more mass shootings than any other state, with 23. While some locations have simply become shorthand for the tragedies that occurred there, others have added tragic phrases to the national vocabulary.

Hover to read about each incident

Post offices

One of the most notorious workplace shootings was carried out by an ex-Marine in an Edmond, Okla., post office on Aug. 20, 1986. The 44-year-old part-time mail carrier, who had gotten a poor performance review the day before, entered the post office wearing his mailman’s uniform and carrying three handguns in his bag. He killed 14 and wounded six before shooting himself. It was the deadliest in a series of rage-fueled killings by current and former postal employees that gave rise to the phrase “going postal.”

Schools

The April 20, 1999, killing of 12 students and a teacher by two disgruntled seniors at Columbine High School in Littleton, Colo., became a turning point after which school shootings could no longer be considered unthinkable aberrations. After a confused response that played out over several hours while a teacher bled to death, U.S. law enforcement agencies overhauled procedures and officer training to create protocols for stopping an “active shooter.”

The graphics below were originally published in December 2015.

A small percentage of total gun deaths

People killed in mass shootings make up less than half of 1 percent of the people shot to death in the United States. More than half of gun deaths every year are suicides. In 2015, more than 12,000 people have been killed by guns, according to the Gun Violence Archive.

25,000 gun-related injuries in 2015 12,000 gun-related deaths 39 deaths from mass-shootings 25,000 gun-related injuries in 2015 12,000 gun-related deaths 39 deaths from mass-shootings

How different databases count shootings

Here are examples of sources that tally mass shootings and the criteria they use. None is comprehensive, because a repository of comprehensive data doesn’t exist. A 2013 investigation by USA Today found that even the FBI’s data on mass killings is only about 57 percent accurate.

Dr. Grant Duwe, “Mass Murder in the United States: A History.” 141 incidents from 1965 through Oct. 1, 2015 At least four people killed in a public place, not including the shooter. The shooter is not included in the total, even if they were killed or injured. Excludes incidents involving other criminal activity. ’65 ’75 ’85 ’95 ’05 ’15 KILLED 40 0 INJURED 60 FBI 2014 study of active shooter incidents 160 incidents from 2000 through 2013 One or more individuals actively engaged in killing or attempting to kill people in a populated area. An active shooter situation is one in which a shooting is in progress and may not necessarily be related to a mass shooting. ’05 ’15 40 0 60 Mother Jones 72 incidents from 1982 through Oct. 1, 2015 At least four people killed in a public place not including the shooter; three or more beginning in January 2013. Shooters who died or were injured are included in the total. Excludes incidents involving other criminal activity. ’85 ’95 ’05 ’15 40 0 60 Mass Shooting Tracker 1,052 incidents from 2013 through Dec. 2, 2015 At least four people shot (not necessarily killed), including the shooter. The shooter is included in the total. ’15 20 0 20 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Dr. Grant Duwe , “Mass Murder in the United States: A History.” 141 incidents from 1965 through Oct. 1, 2015 At least four people killed in a public place, not including the shooter. The shooter is not included in the total, even if they were killed or injured. Excludes incidents involving other criminal activity. Virginia Tech 40 KILLED 32 killed, 15 injured 0 Pacific Southwest Airlines Flight 1771 Aurora theater All 42 killed in crash after gunfire onboard 12 killed, 58 injured 60 INJURED 40 FBI 2014 study of active shooter incidents Virginia Tech 32 killed, 17 injured 160 incidents from 2000 through 2013 One or more individuals actively engaged in killing or attempting to kill people in a populated area. An active shooter situation is one in which a shooting is in progress and may not necessarily be related to a mass shooting. 0 60 Mother Jones 72 incidents from 1982 through Oct. 1, 2015 Virginia Tech 40 At least four people killed in a public place not including the shooter; three or more beginning in January 2013. Shooters who died or were injured are included in the total. Excludes incidents involving other criminal activity.. 33 killed, 23 injured 0 60 40 Mass Shooting Tracker 1,052 incidents from 2013 through Dec. 2, 2015 0 At least four people shot (not necessarily killed), including the shooter. The shooter is included in the total. 60 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Dr. Grant Duwe , “Mass Murder in the United States: A History.” 141 incidents from 1965 through Oct. 1, 2015 At least four people killed in a public place, not including the shooter. The shooter is not included in the total, even if they were killed or injured. Excludes incidents involving other criminal activity. Virginia Tech 40 KILLED 32 killed, 15 injured 0 INJURED Pacific Southwest Airlines Flight 1771 Aurora theater All 42 killed in crash after gunfire onboard 12 killed, 58 injured 60 FBI 2014 study of active shooter incidents Virginia Tech 40 160 incidents from 2000 through 2013 32 killed, 17 injured One or more individuals actively engaged in killing or attempting to kill people in a populated area. An active shooter situation is one in which a shooting is in progress and may not necessarily be related to a mass shooting. 0 60 Mother Jones Virginia Tech 72 incidents from 1982 through Oct. 1, 2015 40 33 killed, 23 injured At least four people killed in a public place not including the shooter; three or more beginning in January 2013. Shooters who died or were injured are included in the total. Excludes incidents involving other criminal activity. 0 60 Mass Shooting Tracker 40 1,052 incidents from 2013 through Dec. 2, 2015 At least four people shot (not necessarily killed), including the shooter. The shooter is included in the total. 0 60 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Sources: Mother Jones; Dr. Grant Duwe, author of “Mass Murder in the United States: A History;” Violence Policy Center, FBI 2014 Study of Active Shooter Incidents; Mass shooting tracker; USA Today data; published reports Notes: Death tolls include all victims killed by shooters within a day of the main shooting, including any who were killed in another way. Totals also include people who later died from injuries received during the shootings. Sources disagree on some ages in this dataset. This graphic has been updated with additional examples of mass shootings that fit our criteria. In a previous version of this graphic, a production error caused the District of Columbia to be counted as a state, misrepresenting the number of states that have had mass shootings. Firearms that were used in events outside our methodology were erroneously included and have been removed. Additional work by , and .