It has been a quarter-century since the massacre at Columbine High School.
On April 20, 1999, two teenage gunmen shot and killed 12 students and a teacher in Littleton, Colorado, before turning their guns on themselves.
It ushered in the modern era of school shootings, and polls ever since have captured the fears of many parents that their children are in danger when they go to school.
In those 25 years, the number of people killed with guns on school property has climbed to least 493, David Riedman, the creator of the K-12 School Shooting Database, told Newsweek. At least 138 of those people were killed in active shooter incidents on school grounds.
But determining exactly how many “school shootings” have occurred in the U.S. since Columbine is complicated. It depends on how the term is defined—and can range from just eight to more than 2,000.
The K-12 School Shooting Database uses an inclusive definition that includes any incident…
