A new, government-backed study answers a question that has been on the minds of some Americans amid this summer’s headlines from Charleston, Chattanooga, and Lafayette. According to the research, mass public shootings are indeed occurring more frequently than ever before in the United States.

The findings, published by the Congressional Research Service (CRS) last week, show that the average rate of mass public shootings has increased from one incident per year in the 1970s to 4.5 incidents per year from 2010 through 2013. The numbers corroborate a 2014 report from Mother Jones. Scholars from the Harvard School of Public Health and Northeastern University independently analyzed data that Mother Jones had collected, and the results showed a marked rise in the frequency of mass shootings in the last three decades. Notwithstanding the recent cluster of high-profile incidents, the CRS report also finds that over the past 14 years, the rate of increase has tapered off.

The definition of “mass shooting” is hotly contested among gun rights and gun safety groups, which criticize each other’s findings as being either too broad or too exclusive. The FBI defines a mass shooting as a multiple-homicide incident in which four or more victims, not including the perpetrator, are killed with firearms in one or more nearby locations. The data compiled by Mother Jones uses a nearly identical definition: the public murder of four or more people in which the shooter and the victims generally were unrelated and unknown to each other.

Here’s a chart from the Mother Jones analysis detailing the number of days between mass shootings:

Mother Jones
Mother Jones

And here’s how the CRS’s time-between-shooting data plots out:

Screen Shot 2015-08-03 at 8.49.20 PM

The CRS study breaks down multiple-homicide shootings into separate, more granular categories. It uses “mass shooting” to refer to incidents in which four or more people are shot to death in a single event in one location, or several locations close to one another. A “mass public shooting” is defined as a multiple casualty event not related to underlying criminal activity or an interpersonal dispute in which the victims are not murdered in private residences or secluded settings. A “familicide mass shooting” is a multiple casualty incident in which the victims are members of the shooter’s family. And a “felony mass shooting” covers gun deaths of four or more people that are linked to separate criminal activity.

A 2013 investigation by USA Today found that the FBI routinely left events that could be defined as mass shootings off of its tally. The CRS authors recommend that Congress consider directing federal agencies, including the FBI, to improve data collection on multiple-victim homicides.

Overall, the report tallied 66 mass public shootings from 1999 to 2013, with a death toll of 446.

By comparison, there were 127 mass shootings involving family members, leaving 576 people dead.

Read the full report here:

[Photo: SearchNet Media]