The enduring power of the Sept. 11 attacks is clear: An overwhelming share of Americans who are old enough to recall the day remember where they were and what they were doing when they heard the news. Yet an ever-growing number of Americans have no personal memory of that day, either because they were too young or not yet born.
https://www.pewresearch.org/politics/2021/09/02/two-decades-later-the-enduring-legacy-of-9-11/