When Bart discovers a badger living in Santa’s Little Helper’s dog house, he turns to Lisa for help. She suggests a woodpecker to lure the badger away, but Bart’s attempt at using the Flanders’ bird for bait fails. Lisa then convinces her father to phone animal control. But when Homer dials, he gets a recorded message asking him to make sure he used the correct area code. Marge explains that the phone company split the town into two area codes; East Springfield was allowed to keep the old one, but a new number was imposed on those in the western half of the city. Homer’s frustration grows when the new area code costs him free tickets to a Who concert being given away by a local radio station. Residents gather at town hall, where a Phone Company Lady shows them a promotional film featuring mascot Phoney McRingring. When the film ends, most townspeople are convinced that the new area code is good for the city. But Homer claims he injured his finger dialing the new numbers. The angry group divides in two: the 636ers and the 939ers. Homer proposes that his group break away and form their own city. People cheer and carry Homer off on their shoulders.

Tensions mount between the people of East and West Springfield: Mayor Quimby proclaims that his people have a superior town bird; Marge is forced to pay an out-of-towner tax at the Kwik-E- Mart; Bart is harassed by bullies who claim that everything in their area code belongs to them. When Homer, now the town mayor, realizes that East Springfield believes it is the better community, he vows to take action. He makes his way to the power plant…and plunges the east side of town into darkness. A tit-for-tat soon develops: the East dumps the West ’s mail into a river; the West runs the East’s water supply dry, and so on. Eventually, Homer calls for the construction of a wall separating the two communities. Soon after, those in the West realize they cannot live without the hospitals, schools and banks in the East…and begin streaming over the wall.

As the Simpson family walks along the wall of the now-deserted West Springfield, Bart remarks that his father is the mayor of a ghost town. Homer declares that once the defectors learn about the upcoming Who concert, they will return. Marge reminds him that the concert is located in East Springfield. Homer, however, is undeterred. He and his family make their way to a hotel, where Homer asks for the group’s help in saving his city. Eventually, the Who opt for a change in venue. Instead of performing at the East Springfield arena, where an expectant crowd awaits, they assemble atop the wall facing west. When confronted by angry Easterners, the Who urges everyone to set aside their differences and purchase phones with speed-dialing capabilities. A section of the wall topples over, and Easterners pour through to hear the concert. Unbeknownst to them, an army of badgers prepare for an attack.