The Simpsons Season 20 Episode 21

Krusty's new eco-burgers bring food poisoning to Springfield thanks to contaminated barley,an ingredient imported from neighboring Ogdenville. Conssequently the Ogdenville economy plummets and its citizens,descendants of Norwegians,migrate to Springfield where they are initially welcomed for their industry. However their customs start to swamp those of Springfield and Quimby decrees that a wall be built to keep any more incomers at bay. The Ogdenvillers are allowed to help in its construction,during which time a strange new bond forms between the two townships.