In this image released by CBS, actors, from left, Herb Nelson, Ellen Demming, Susan Douglas and Lyle Sudrow appear in the premiere TV broadcast of “Guiding Light” on June 30, 1952. After 72 years on the air, the longest-running television drama broadcast weekdays on the CBS Television Network, will air its final episode on Sept. 18, 2009.

New York ? CBS is pulling the plug on the soap opera “Guiding Light” after a 72-year run that predates television, the show a victim of the economy and changed viewing habits.

The drama’s final episode will air on Sept. 18.

The Guinness Book of World Records has cited it as the longest-running television drama. It began as a 15-minute serial on NBC Radio on Jan. 25, 1937, and debuted on CBS TV in 1952, focusing on the fictional town of Springfield and the Spaulding, Lewis and Cooper families.

“For many of us, it was the first show we ever watched,” said Lynn Leahey, editorial director of Soap Opera Digest. Unlike prime-time shows that came and went, it was a constant in people’s lives. “It really is heartbreaking to see something like this go away.”

Procter & Gamble Productions, which makes the show, informed cast and crew Wednesday at separate sets in New York and New Jersey. The company isn’t giving up on the story, and will explore different ways to keep it going after September, a spokeswoman said.

Soap operas have been in a long, slow decline in popularity, primarily because many of the women who made up their loyal audiences are no longer at home at that hour. They’re working, and can find the communal experience that their favorite soaps once gave them elsewhere.

“Guiding Light” had the lowest ratings of the eight daytime dramas on the air. When it leaves, CBS and ABC will have three weekday soap operas, with NBC having one.

“The numbers are really tough for all of these old dramas,” said Ron Raines, the actor who portrayed the villain Alan Spaulding in “Guiding Light.”

“I don’t think any of the other shows want any of us to go off. We’re all in this together,” he said.

Many successful actors got their start on “Guiding Light,” including James Earl Jones, Calista Flockhart, Hayden Panettiere, Kevin Bacon and Taye Diggs.

Faced with extinction a year ago, “Guiding Light” significantly revamped its operations. It ditched its fixed, three-camera set in favor of portable cameras that enabled producers to shoot in different locations. The move saved money and changed the show’s look to make it seem more like the reality shows younger viewers are accustomed to.

It didn’t work, at least enough for CBS. The network hasn’t said what will replace “Guiding Light” on the schedule, but it will almost certainly be a talk or game show, which are much cheaper to make than dramas with a large cast.