The Columbine killings of 1999 failed to provoke any shift in Americans' attitudes to guns.

ECONOMIST: Americans still don't want more gun control

It spread to the country's schools in 1994, when President Clinton's Gun-Free Schools Act required them to suspend for a year all students caught bringing guns on to their premises, and has been gathering momentum ever since, particularly after the gruesome killings at Columbine High School in Littleton, Colorado earlier this year.

ECONOMIST: Jesse Jackson��s wrong target

For survivors of Columbine and other tragedies, there's a serious danger when new mass killings stir up memories, says clinical psychologist Paula Bloom.

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