Minnesota Public Radio's The Morning Show was broadcast live from the Minnesota State Fair this morning. During that broadcast, this accordion player (sorry, can't remember his name) played a coupled of times. He said he'd play the theme song to a TV show. When the audience was asked how many people knew who played the accordion on that show, I was the only person under 40 (as far as I could tell) who knew the answer, and I held my hand high with pride. So, if you're under 40 or 50, I don't expect you to know this theme song. Can you guess what show it's for?

Answer below as response to Loonachic's comment.