墨西哥合众国（西班牙语：Estados Unidos Mexicanos）是一个北美洲国家，北部与美国接壤。
In the episode “Probably”, Kenny arrives in Ensenada, Mexico after a bus drags him over the border. Eric Cartman is later sent to the same town when his church is shut down and Jesus Christ reasoned that it was a fate worse than Hell.
Mexico is the main focus of the episode “The Last of the Meheecans”, during which Butters Stotch, as Mantequilla, inspires the Mexicans to immigrate back to Mexico from the US. The Mexican President, Felipe Calderón, reappears in this episode with a talking role.
- “Summer Sucks” - Jimbo and Ned buy fireworks here.
- “Probably” - Kenny is dragged to Mexico by a bus. Cartman is later sent her by Jesus.
- “Free Willzyx” - The boys use the Mexican Space Program to send Jambu to the moon.
- “Pinewood Derby” - Randy is upset at Mexico for building a bunch of water parks with the space cash.
- “The Last of the Meheecans” - Butters convinces Mexicans to immigrate back to Mexico.