The Simpsons (1989): Season 20, Episode 21

20 - 21: Coming to Homerica

When nearby Ogdenville's economy crumbles due to tainted barley discovered in Krusty's veggie burgers, the unemployed workers of Ogdenville flock to Springfield. After Mayor Quimby closes Springfield's borders and enlists private citizens to help patrol them, Homer organizes a border patrol group.