"AMERICAN TOP 40" with host Casey Kasem, who died Sunday at age 82, was born on the Fourth of July, literally - July 4, 1970. It was amazing timing, to say the least - less than two months after the bloodshed at Kent State (the No. 30 song, played by Kasem that week, was "Ohio" by Crosby, Stills, Nash & Young), six months after Altamont, and with the Beatles breaking up and their final No. 1 recording, "The Long and Winding Road," also on the chart at No. 8 that week.

The center was not holding.

But Kasem was the right man for that strange time. He took the chaos that was American pop music and turned it into something that no one had ever thought it could be: a story, that had heroes with remarkable backstories that he could now reveal to the audience, that had winners moving up and losers moving down every week, counting down to an operatic denouement at the No. 1 position. Rock, pop, soul and country became a kind of Greek-style mythology in his accessible tenor.

But there was a huge irony in the amazing success of "American Top 40" - while it celebrated the notion of a national mass culture, it was still powerless to prevent that mass culture from shattering into a million pieces. It was an evolutionary midpoint, as Casey and the show's syndicator Westwood One used better technology and the advanced capitalism of modern marketing to take what could only be done locally - a guy playing records and beaming a signal from a large tower - and make it into a weekly national event.

But as syndicated FM stations proliferated and then finally the Internet with Spotify and Pandora and (yes) satellite radio and, of course, iTunes provided a home for every musical (and nonmusical) niche imaginable, no one could any longer see the purpose of a shared "Top 40 radio." Something is gained in the libertarianism of 21st-century pop culture, perhaps, but something has been lost, a sense of community and shared feelings and emotions that many of us feel difficult to even express in words.

So when "American Top 40" ended its run in 1988 (Kasem continued variations of "Countdown"-style shows for two more decades, even on TV), it wasn't really with a sense of "mission accomplished." It was more like he'd been putting his fingers in the leaky dikes of U.S. mass culture for almost 20 years, but there was nothing more he could do to hold off the flood.

There are - and there will be - other cheerful voices coming out of the speaker, other "personalities" on the radio or the Internet or inevitably on some future device that exists today only in the mind of some freshman at MIT. Those fresh voices will know how to tell a good story and hold our interest, at least for a couple of minutes.

But there won't be that one voice that will bring so many different people together for three hours, in such a unique time as the heyday of Casey Kasem. This is why so many people are mourning his loss. There will never be another one like him.