Today an NPR reporter described the Virginia Tech tragedy as "the biggest mass killing in US history." Well no, there were something like 80 Branch Dividians killed at Waco. And when the Japanese bombed Pearl Harbor, over 2,000 Americans died.
I suppose you could give them the benefit of the doubt, and say that they realized Hawaii wasn't a state at the time of Pearl Harbor, and hence doesn't count as a mass killing in "US history."
But no, of course the real reason for the discrepancy is that when government employees kill people (at least on "official business") it doesn't count.
Having said that, I don't know how to deal with the omission of the 9/11 attacks.
To their credit, the stories I read yesterday about campus killings included the Kent State incident.