Philadelphia ? It was an interesting juxtaposition, what happened Monday. Just hours after another unknown name crossed the finish line first at the Boston Marathon, Lance Armstrong announced he would retire as an active cyclist following this summer’s Tour de France.

If you are of my era, you know what marathon running once was on the American sports landscape. People cared about it, knew who Bill Rodgers was, knew who Frank Shorter was, knew and admired the efforts of Alberto Salazar in some memorable marathons of the early 1980s.

In 1982, Salazar pushed through a brutal day in Boston, then outlasted Dick Beardsley in one of the most memorable moments of my 24-year sports-writing career. Beardsley was bumped by an exuberant motorcycle cop as he tried to regain the lead he had lost down the final eighth of a mile. Salazar pushed himself so hard in the day’s unusual heat, he nearly died. A doctor described him as a “potato chip.” It all seems like yesterday. Those things tend to stay in your mind.

My guess is that’s what Lance Armstrong will provide us with 20 years from now: performances that stick in the mind. A story too compelling to forget.

And a reference point to the apex of cycling’s popularity.

An extraordinary athlete who pushed an obscure sport — at least to Americans — into public consciousness, an athlete who forced newspapers and networks to make room in their budgets for Tour de France coverage, Armstrong personified his sport the way Pele personified soccer to Americans in the late 1960s and early 1970s.

If you asked people then to name another soccer player, they couldn’t. If you asked Americans Monday to name another cyclist — from any nation — most couldn’t, either. One person, a 12-year-old player on my Little League team named Brian Donovan, who is smarter than his years, knew Jan Ullrich, Armstrong’s chief rival. He even commented on how Armstrong’s retirement opened the door for him.

The rest I asked, mostly adults, didn’t know.

And, frankly, didn’t care.

What Lance Armstrong has done athletically stays in your mind. Six straight Tour de France victories for an American is almost the equivalent of six sumo titles for an American in Japan. It’s not supposed to happen, ever.

Said Jonathan Vaughters, one of Armstrong’s rivals, in the Atlanta Journal Constitution on Sunday: “Guys who he had to go head-to-head with, who were immensely talented, like Joseba Beloki, like Jan Ullrich, like Alex Zuelle, for those guys who were all well-deserving of wins in the Tour de France, who should have won more than one Tour de France on their own right. That was just torn away from them by someone who was just physically and psychologically superior. I’m sure that’s very tough for them to deal with. They were basically born at the wrong time.”

Kind of like a sports writer born in 1982. To him or her, marathon running is about as entertaining as the Wall Street ticker that runs along the bottom of cable channels.

Maybe the American kids born this year will not know about Lance 20 years hence. Lord knows Pele, who once was as popular here as Muhammad Ali, is another name that draws blank stares from the under-30 crowd.

Or maybe Armstrong will become like Ali, whose legend and achievement seemed to improve as his health declined.