The continuing success of Journey's "Don't Stop Believin'" is a head-scratcher.

The song, which peaked at No. 9 on the pop charts in 1981, isn't even the Bay Area band's biggest hit. That would be "Open Arms" (No. 2 in 1982), followed by "Who's Crying Now" (No. 4, 1981) and "Separate Ways (Worlds Apart)" (No. 8 in 1983).

Nevertheless, "Don't Stop Believin'" continues to be a pop-culture force today, even used as the finale for the current "American Idols Live" tour, where all the finalists get a crack at a few lines from the classic. And, according to Nielsen SoundScan, it was the top music download from the '80s as of the end of July, ahead of seven Michael Jackson songs, Bon Jovi's "Livin' on a Prayer" and Survivor's "Eye of the Tiger." (This week, the song was still among iTunes' Top 100 downloads -- the oldest song on the current list by far -- as was a cover version by the cast of "Glee.")

"The lyric is a strong lyric about not giving up, but it's also about being young," former Journey singer Steve Perry told the Canadian Broadcasting Corp. recently about the song he wrote with keyboardist Jonathan Cain and guitarist Neal Schon, who continue with Journey. "It's about having hope and not quitting when things get tough, because I'm telling you, things get tough for everybody."

Maybe that's why "Don't Stop Believin'" lives on and on and on.

Here's a look at some of its recent incarnations:

"The Sopranos" (2007)

Used as: The theme music for the HBO series' final scene, a seemingly regular family meal at a diner that feels ominous, especially when the song cuts out after "Don't stop" and the screen goes black.

The reaction: The song had an immediate resurgence following its part in the scene, which became so iconic that Hillary Clinton even parodied it as part of her presidential campaign.

"Rock of Ages" (2009)

Used as: The finale of the Broadway musical, where the entire cast gets together and ties up story lines.

The reaction: The scene helped "Rock of Ages" land a Tony nomination for best musical and a nod for Constantine Maroulis as lead actor in a musical.

"Glee" (2009)

Used as: The main number in the first episode of the new Fox series about a high-school glee club.

The reaction: The cast's version was an overnight sensation, landing at No. 4 on the pop charts on the strength of its download sales alone.