The story
From the name of the fictional town Lake Wobegon, created by Garrison Keillor as the setting of the recurring segment “News from Lake Wobegon” for the radio program A Prairie Home Companion, aired live from 1974 to 2016 from Saint Paul, Minnesota. The figurative senses derive from recurrent elements of the monologue, specifically “the little town that time forgot and the decades cannot improve” and “Lake Wobegon, where all the women are strong, all the men are good-looking, and all the children are above average”.
Etymology from Wiktionary, CC BY-SA 4.0.