The deadliest school-killing in American history was in 1927, killing 38 children and 6 adults and wounded about 60 more. The killer was the school board treasurer and had spent the previous few months buying and stealing dynamite around his farm and the school as well as his truck.
The difference since Columbine is the celebration of mass shootings. The media makes celebrities out of the killers and make graphics breaking down the planning, supplies, tactics, and more. They’re essentially helping the next maniac plan a “better” killing.