Coming to Homerica

S20 E21: When Krustyburger serves tainted barley, the barley suppliers in Ogdenville are forced out of work. They emigrate to Springfield, where they prove to be hardworking and polite. But as they become more and more a part of Springfield's daily life, Homer and his friends form a border brigade to keep them out, culminating in the building of a wall between the two cities.