The shooting at the Navy Yard in Washington, D.C., on Monday marks the 20th time since Barack Obama took office that there has been a mass killing incident. Using data compiled by Mother Jones magazine, we created an animated map to show, month-by-month, what that toll looks like.
According to that data, 174 people have lost their lives since January 2009 in such incidents. The incidents must meet several criteria: four or more killed, it must have been a solitary shooter, the killings must have happened in a public place or series of places. Here's what the killings have looked like. (Note: not all months saw such killing, happily.)
We've looked at Mother Jones' data before, using it to analyze the effect that the Senate's fairly weak gun control measures might have had if they'd been approved earlier this year. (Our assessment: not much.)
That map makes clear why the issue is so resonant with the president, who noted the spate of killings in his speech on Monday. No president has seen more incidents than Obama, as you can see at right, except President Clinton, whose two terms saw 23 killings to Obama's 20.
But, then, Obama has three more years to go. His administration has seen more killings on a per-month basis than any of the four proceeding.