1. Mass shootings appear to have become more common
There are different definitions of mass shootings. But the bottom line is that such incidents appear to have become more common in recent years.
Investigative news outlet Mother Jones has compiled decades’ worth of data about mass shootings. It defines a mass killing as the killing of at least four people in a public place in which the motive appeared to be indiscriminate killing.
Between 1982 and June 12 of this year, there were at least 83 incidents that fit the Mother Jones definition of a mass shooting. Forty-six — more than half — have occurred since 2006, including 7 in 2015 alone.
Researchers from Harvard and Northeastern University released a study in 2014 using the Mother Jones data and found that the rate of mass shootings had tripled since 2011.
2. In fact, there were more mass shootings than days in 2015
The Mass Shooting Tracker is a project that tracks incidents in which four or more people are shot — but not necessarily killed — in a single spree or setting.
By its count, there were 371 such incidents in 2015. That meant there were more mass shootings than days, an oft-cited statistic. Those incidents killed 469 people, and wounded 1,387.
Where mass shootings occurred in 2016
This map is based on data from the Mass Shooting Tracker, which defines a mass shooting as a single incident in which four or more people are shot, regardless of whether they were killed. The definition allows for the shooter to count toward the four or more threshold. Others define mass shootings differenty. (Note: The size of each dot reflects the number of people who were shot.)
Matt Rocheleau/Globe Staff
3. Active shooter incidents are also on the rise
The FBI in 2014 released a look at “active shooter” incidents. An active shooter incident, to the FBI, involves one or more people “actively engaged in killing or attempting to kill people in a confined and populated area.”
The agency counted 160 such incidents between 2000 and 2013, and noticed a rising trend.
The FBI this year released new data for 2014 and 2015 finding that the upward trend continued, with 20 active shooter incidents in each year.
4. The term ‘active shooter’ has rapidly become a part of our vocabulary
The Washington Post researched online search data from Google Trends to find how use of the two-word term has risen sharply in recent years.
5. Gun ownership in the US has declined overall
Gun ownership is at the lowest level in the US since at least the early 1970s.
In 1973, 47 percent of American households reported having at least one gun. That figure peaked in 1977 at 50.4 percent, according to the most recent General Social Survey report by the University of Chicago. But since then it has trended downward.
In 2014, 31 percent of households in the US said they had a gun.
6. So, too have gun homicide rates
The Pew Research Center reported that the gun homicide rate in the US peaked in 1993 and has declined since, even amid the rise in mass shootings, which account for a relatively small number of gun homicides. As of 2010, the rate was 49 percent lower than the 1993 rate.
7. But both gun ownership rates AND gun death rates in the US are much higher than in any other highly developed country
The Small Arms Survey found that there were 88.8 civilian-owned guns per 100 people in the US as of 2007. The next highest rate was 54.8 civilian-owned guns per 100 in Yemen.
According to 2012 data from the United Nations compiled by the Guardian news outlet, the US has the highest rate of firearm homicides among highly developed nations, 29.7 gun killings per 1 million people.
Active shooter incidents are also more common in the US than in other countries, according to J. Pete Blair, a criminal justice researcher from Texas State University, who has closely researched such attacks.
Another stunning piece of data: Guns have killed more Americans in just the past half century than every war in US history, according to news website Vox.
8. That fits with a pattern of there being more violence in US than in most other developed nations
A Duke University researcher found the rate of assault deaths in the US to be higher than in other than in most other nations in the Organization for Economic Cooperation and Development.
9. Many gun experts believe strong gun laws reduce killings
Numerous studies have found that states with stricter gun laws tend to have fewer gun deaths.
The Harvard Injury Control Research Center polled dozens of leading gun experts, finding that a majority believe that having a gun in someone’s home can make it a more dangerous place.
The following chart shows how about 100 experts responded when the center posed this question to them:
10. Support for gun rights has increased, even in the wake of gun massacres
Polls by the Pew Research Center have found increasing support for protecting gun owners’ rights over the past 20 years, while support for measures to control gun ownership has trended downward over the same period.