I was 16 when 9/11 happened and have pretty clear memories of adults' responses. Exactly zero Americans took 9/11 "pretty calmly". https://twitter.com/paulkrugman/status/1304385740063805440

Sixteen is one of those ages where you're technically old enough to understand the enormity of what is happening but are still young enough to look to adults to signal how you should respond to it, and on 9/11 and the years afterward, no adults knew how to respond.

I grew up in upstate NY and I remember one of my mom's coworkers told her "I found myself looking for snipers in the mountains as I drove up the highway to work this morning. Which is insane. There are not going to be snipers in the Adirondacks. But I was doing it."