Guns in the U.S.: We’re better at killing Americans than our enemies are
Los Angeles Times - 10/06/2015
The Federal Bureau of Investigation defines a mass murder as four or more deaths during a single incident with no distinct time period between killings. By this definition, according to Northeastern University criminologist James Alan Fox, between 1980 and 2010 there were an average of 20 mass murders per year, or an average of one every 2.6 weeks.
Now it looks like that interval is shrinking. According to shootingtracker.com, there were 30 mass public shootings with four or more dead in 2014, and there have been 31 this year through the Oct. 1 tragedy in Roseburg, Ore., or one every 1.6 weeks.