Here's a short list of projects attempting to count either gun-related casualties and/or mass killing events in America:
The FBI gets a lot of criticism for undercounting or miscategorizing mass shooting incidents. But it’s worth having a base definition:
An active shooter is an individual actively engaged in killing or attempting to kill people in a populated area, and recent active shooter incidents have underscored the need for a coordinated response by law enforcement and others to save lives.
This official report is purportedly based off of a dataset of 160 incidents with 486 people killed.
After the 2012 mass shooting in Aurora, Colorado, Mother Jones launched a five-month special investigation focusing on American gun laws and the apparent rise in mass shootings. Their project included an online database of mass shootings from 1982-2012, which they have updated with major shootings through 2015.
This investigation found that mass killings in America happened “far more often” than what the government reports, and that their circumstances and the weapons used “are far more predictable than many might think.”
One astonishing takeaway from USA Today’s reporting (emphasis added):
While only about 1% of all murders nationally, mass killings still happen frequently. The FBI counted 172 cases of mass killings between 2006 and 2011. That does not include some large states such as Florida, for example. Poor reporting by police agencies to the FBI also means some mass killings were left out, while others that don’t meet the standard were included.
The answer to the simple question in that headline is surprisingly hard to come by. So Slate is collecting data for our crowdsourced interactive.
An online archive of gun violence incidents collected from over 1,200 media, government and commercial sources daily in an effort to provide near-real time data about the results of gun violence.
This database contains U.S. mass shooting incidents – and their associated geospatial data – over a span of five decades.
Unlike with U.S. police-involved homicides, Wikipedia users have not initiated a seperate project for general mass killings in the United States.
An interactive map of American gun violence based off of the The Gun Violence Archive.
A rundown of inconsistencies and omissions in the FBI’s voluntary reporting system of mass killings.
This report contains the FBI’s definition for mass murder – a number of murders (four or more) occurring during the same incident, with no distinctive time period between the murders – to distinguish it from serial murders.
What Slate learned from trying, and failing, to record every death by gun in America since Newtown.
How many mass shootings have occurred in 2015? And how do you define "mass shooting," anyway?
In the wake of the San Bernadino massacre, why is it that Mother Jones and the crowd-sourced Mass Shooting Tracker database differ so widely?
What’s the difference between a “mass shooting” and a “mass killing”?”
An interview with Patricia Carbajales and her motivation for creating the Mass Shootings database while at the Stanford Geospatial Center.
Survey Report For the first time in more than two decades of Pew Research Center surveys, there is more support for gun rights than gun control.
A look at how frequently mass shootings occur
A dataset of two decades compiled after the 2012 Aurora, Colorado theater shootings. After the publication of the project in 2012, the database has been occasionally updated with major shooting events. The spreadsheet also contains a separate sheet categorizing the weapons used in each incident.
This wiki of mass shooting data has been maintained by the users of Reddit’s r/GunsAreCool subreddit since 2013.
A mass shooting is when four or more people are shot in an event, or related series of events, likely without a cooling off period.
Among the datasets listed here, USA Today has the most comprehensive and complex data schemas, with separate JSON files for events and victims.
To analyze mass killings, USA TODAY used the FBI’s definition: 4 or more killed, not including suspects, in an event. The killing may stretch over a day or more and some distance, especially if it includes killings committed in flight or against targeted people. It does not include an extended “cooling-off period” to distinguish this kind of crime from the acts of serial killers.
A data project that attempted to record each gun-related death in America. At the end of the year, Slate wrote about why the project failed.
This dataset did not limit its count to mass killings by gun, but any death caused by a gun. Ultimately, they counted roughly 11,000 reported gun deaths in 2013. The Centers for Disease Control and Prevention reported 32,163 deaths.