Twenty years isn't just the measure of how long the United States has been in Afghanistan.
It's also the measure of how long it's been since anyone old enough to have memories from 2001 have had the experience of watching the fall of the World Trade Center towers etched in our minds.
On that Tuesday morning, I watched the events play out in New York from a little house on Stearns Street in Fayetteville. It was the first house my wife and I shared as we approached our two-year anniversary later that month.
Every generation has those moments we cannot erase from our minds. There are incredible moments, like the 1969 moon landing I don't really remember. I was 3 1/2. But I do remember the fascination I had in the early '70s when astronauts rode around on the moon's surface in the lunar rovers, three of which remain on the moon's surface today.
There are plenty of tragic memories, unfortunately. I had just finished my paper route in Little Rock on Aug. 16, 1977, and made my traditional weekday stop at my great aunt's house on West 59th Street for a much-appreciated drink. The Arkansas Democrat was an afternoon paper at the time Monday through Friday.
It was there she showed me the shocking TV coverage of Elvis Presley's death. Not many people can equate to the legendary status to which Elvis had risen. I suppose others have similar "where was I" recollections involving John Lennon, Michael Jackson, Prince, Whitney Houston and Kobe Bryant.
The attempted assassination of Ronald Reagan on a March afternoon in 1981 left me mesmerized by TV coverage. CNN had launched its 24-hour cable news coverage less than a year before the attack, but ABC's coverage produced those first haunting scenes of confusion amidst bodies on the sidewalk.
I also recall bouncing down some stairs at Arkansas State University's phys-ed building in 1986 when I overheard someone comment about an explosion of a space shuttle. I thought it was a bad joke. When I got to the Journalism Department, I learned the Challenger had indeed been destroyed and the astronauts lost.
Nothing, though, has ever matched my pit-of-your-stomach moment of Sept. 11, 2001. It didn't come when news broke that a plane had struck one tower of the behemoth World Trade Center. The moment that made me sick with the realization our world had just undergone a seismic-level shift came when the second plane struck the other tower. Everyone watching knew then this had been no accident.
I was editor of the Northwest Arkansas Times then, having accepted that role earlier in the year. The morning's events pretty much erased any plans our newsroom had that day. The cascade of cancellations started quickly and didn't let up. Going about "normal" business just didn't seem all that important at the time. I remember the staff doing a great job of finding local stories for the next several days even though we were 1,300 miles from the attacks. Northwest Arkansas, like the rest of the world, was shaken.
Saturday marks the anniversary of those attacks, which don't seem that long ago. I knew, of course, that the post-attack unity of Americans wouldn't last forever. I had no idea 20 years later there would be so many examples of its absence in our communities and around the nation. It's certainly missing from our politics. It's certainly missing from social media. And it's missing from too many of our relationships and opinions about others.
Americans have a demonstrated capacity to act with resolve in the face of national challenges. In the 21st century, though, there's a lot of reason to wonder whether that remains a fundamental part of our national identity.