Thanks to an anonymous reader for pointing me in this direction. The Denver Post, in its coverage of the 5th anniversary of the Columbine School shootings, stated that:

Five years ago Tuesday, two Columbine High School students perpetrated the largest mass slaying in the history of the nation's schools, killing 12 students and a teacher before committing suicide. Two dozen others were wounded.

Wrong.

On May 18, 1927, a psychotic named Andrew Kehoe, age 55, blew up an elementary school in Bath, Michigan with dynamite, killing 45 people and injuring 61 others. Columbine may have been the country's worst shooting, but it was not its worst school slaying.

The distinction is important, because without it, you'd never know that schools have long been targets of violence. It might seem like a trivial distinction, except that it bespeaks a laziness and lack of historical perspective that typifies post-me-generation journalism.

None of this makes Columbine any less horrifying. Not if you have to send your kids off to school each morning, and certainly not if you lost someone that day. But it does give it some context that a mere 5-year assessment can't provide.