The article talks about Columbine because it's the 20th anniversary and they need to fit it in, but my perception is that lockdown drills didn't become popular

The article talks about Columbine because it's the 20th anniversary and they need to fit it in, but my perception is that lockdown drills didn't become popular more recently. They cite numbers from 2016... do they have numbers for 1999-2016? My admittedly cynical suspicion is that this has more to do with a shift in gun control strategy and less to do with safety. In the 90s, pre-Heller, gun control efforts mostly focused on handguns using the threat of street crime. With crime rates way down and handgun bans nonviable, gun control efforts have shifted to focus on semi-auto rifles using the threat of mass shootings. Lockdown drills keep children and parents fearful, which encourages voters to support gun control, even though mass shootings are statistically quite rare.