When a donkey rips Bart's shorts off whilst he is standing in front of a screen exhibiting the American flag, he is erroneously taken to be mooning it and he and the family declared to be unpatriotic and, with them, by definition, Springfield. Quimby changes the town's name to Libertyville but the family is still sent to the Ronald Reagan Rehabilitation Center on Alcatraz. They escape and end up in France, which they quite like but decide to 'emigrate' to the New World and start over.
—don @ minifie-1