Notes on Methodology.
This list started as a diversion in 2006 when I realized the FBI was changing the definition of “Mass Killing.” I decided this was an attempt to define the problem away. I began to collect reports from the news media.
While an ideal list would be exactly comparable from year to year, this one is not. As the years went by, I became better able to find reports in local newspapers.
The number of incidents have increased, but at least some of this is because of better reporting.
These lists aim to include:
Criminal killings
Of more than four people
In one “emotional event”
By a single killer
In the United States.
Appling these rules leads to some strange rulings. The Columbine School Killing is not included because there were two killers. Serial killers are not included as there is a long time between each murder. Vehicular homicides count if the driver (the killer) is charged with a crime. If he is killed in the accident he is not charged and so not listed here.
On the other hand, I count other mass killings if the murderer kills himself, and so is never charged.
Most controversially I count a suicide by the murderer. If a person kills three others and himself, that event is included. If he kills three others and is himself slain by the police, the event is not included.
I myself am not completely happy with this. I have learned that it important to have rules, even if they impose limits of my own judgement. The rules are important because they impose limits on my own judgement.
I admit a prejudice towards including events. If a person is charged with a crime and later is found not guilty, I will keep the incident on the list.
I hope everything on the list is correct, but admit some incidents that ought to be here are not. Most likely I simply did not see a news report. I welcome corrections.
Recapitulation
2017
2016 55 291 Orlando
2015 51 238
2014 35 165
2013 29 145
2012 20 134 Newtown
2011 29 152
2010 21 107
2009 30 173
2008 28 140
2007 23 141 Virginia Tech
2006 31 157