The buildings were dingy. Trash cans lined the street. And Cookie Monster not only gobbled fistfuls of cookies but occasionally smoked a pipe.
Now the set's been spruced up. Cookie Monster calls cookies a "sometime" food. And the mood is decidedly more Elmo than Oscar the Grouch.
The show has changed so much that DVDs of the early episodes now carry a warning that they might not be suitable for today's kids.
Yet despite its new image, the show's themes of tolerance and learning persist. In the Middle East, a version broadcast in Hebrew and Arabic brought peaceful giggles in the 1990s. In South Africa, an HIV-positive Muppet helped de-stigmatize the disease.
Sesame Street has always been ahead of its time. It's a window into the world of children, a place where everything's A-okay, and has been for 40 years.
So Happy Anniversary Sesame Street!
That's a page from my notebook.
I'm Katie Couric, CBS News.