In December 2012, a gunman walked into Sandy Hook Elementary School in Newtown, Connecticut, and killed 20 children, six adults, and himself. Since then, there have been at least 1,126 mass shootings, with at least 1,252 people killed and 4,453 wounded.
The counts come from the Gun Violence Archive, a database that tracks events since 2013 in which four or more people (not counting the shooter) were shot at the same general time and location. The database’s researchers comb through hundreds of news stories, police reports, and other sources each day and individually verify the reports. Still, since some shootings aren't reported, the database is likely missing some shootings, and some are missing details. The count is also a constant work in progress, so some of the numbers and details may be slightly imprecise.
Vox’s Soo Oh created an interactive map with this database. It shows the mass shootings that have been counted by the Gun Violence Archive since 2013, after the Sandy Hook shooting:
Are mass shootings increasing? It depends on which definition you use.
Using one common definition — shootings at a public place in which the shooter murdered four or more people, excluding domestic, gang, and drug violence — they appear to be getting more common, according to an analysis from Harvard School of Public Health researchers.
But not everyone agrees with this definition. Northeastern University criminologist James Alan Fox, for example, defines mass shootings more widely, as any shooting in which at least four people were murdered. Under those terms, mass shootings don’t appear to be increasing.
Researchers from the Harvard School of Public Health call the definition Fox uses too broad, since it catches domestic, gang, and drug-related shootings that aren’t usually considered mass shootings in layman’s terms.
The Gun Violence Archive’s definition, which is what's used for the map above, is even broader than Fox’s — counting not just murders but injuries, too. So it counts all shootings in which four or more people were shot but not necessarily killed (excluding the shooter). That includes domestic, gang, and drug-related shootings in which four or more people were killed or wounded, as well.
Even under the Gun Violence Archive’s broad definition, it’s worth noting that mass shootings make up a tiny portion of America’s firearm deaths, which total more than 32,000 each year.
And the US has way more gun violence than its developed peers: According to United Nations data compiled by Simon Rogers while at the Guardian, the US had 29.7 firearm homicides per 1 million people in 2012, while Switzerland had 7.7, Canada had 5.1, and Germany had 1.9.
But why does the US have so many more gun homicides than other developed countries? One possible explanation: Americans are generally much more likely to own guns.
The US makes up about 4.4 percent of the global population but possesses 42 percent of the world’s civilian-owned guns. And the empirical research shows that places with more guns have more homicides.
Criminal justice experts widely recognize that America’s unusually high levels of gun violence are a result of cultural and policy decisions that have made firearms far more available in America than in most of the world. For the US, that means not just more mass shootings, but more gun violence in general.