What some people know (though most probably not) is that the show came about because Keillor was writing an article for The New Yorker about the last performance of The Grand Ol' Opry radio show at the Ryman Auditorium (before it moved location), and that's what spurred his idea to do a Midwestern-style show. And this monologue takes place at that very same Ryman Auditorium, 20 years after his 1974 visit. Which gets him to reminisce about the occasion and what his life was like that pushed him in that direction.
It's a lovely and extremely funny monologue, getting into tales about what the town was like in his early days and what made it special to him. (Noting, for example, that Lake Wobegon has no turn signals because everyone knows which way you're going.) There's even a brief mention of Buster the Fishing Dog, who is the subject of two of my favorite monologues. But perhaps best of all is when he talks about people in Lake Wobegon understanding that "good enough" is...good enough, and that knowing that is the foundation to being happy. And it all ends with a lovely sentence about happiness.