On Wednesday, Syed Rizwan Farook, 28, and Tashfeen Malik, 27, killed at least 14 people and wounded at least 18 more in a mass shooting and subsequent shootout with police in San Bernardino, California. But as appalling the massacre was, mass shootings aren’t uncommon in the United States: In the past 1,066 days, there have been at least 1,044 mass shootings, with shooters killing at least 1,327 people and wounding 3,784 more.

The counts come from the Mass Shooting Tracker, a crowdsourced database that tracks shootings since 2013 in which four or more people were shot. As with any crowdsourced database, it’s likely missing some shootings, and some of the shootings are missing details.

Vox’s Soo Oh created an interactive map with data from the Mass Shooting Tracker. It shows the mass shootings tracked in the database that have been verified with news reports since the December 2012 shooting in Sandy Hook, Connecticut. To view the full interactive version, make sure to click the map below:

Are these types of shootings increasing? It depends on which definition you use.

Using the definition many people operate under — 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 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 that definition too broad, since it catches domestic, gang, and drug-related shootings that aren’t usually considered mass shootings in layman’s terms.

But the Mass Shooting Tracker is even broader — counting not just shootings in which four or more people were murdered, but shootings in which four or more people were shot at all. The database’s organizers explained their reasoning on their website: "For instance, in 2012 Travis Steed and others shot 18 people total. Miraculously, he only killed one. Under the incorrect definition of mass shooting, that event would not be considered a mass shooting! Arguing that 18 people shot during one event is not a mass shooting is absurd."

Even under this broader 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 UN data compiled by the Guardian’s Simon Rogers, 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 advanced countries? One possible explanation: Americans are much more likely to own guns than most of the world — the US makes up about 4.4 percent of the global population, but owns 42 percent of the world’s civilian-owned guns. And the empirical research shows places with more guns have more gun homicides.

Criminal justice experts widely recognize this is 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.

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