The North American country with the official name “United Mexican States” is Mexico.
In Spanish, the constitutional name is Estados Unidos Mexicanos, translated as United Mexican States. The name reflects Mexico’s federal structure: the country is a federation made up of 31 states plus Mexico City, a federal entity. In everyday English, however, the country is almost always called Mexico.
The formal name was established in Mexico’s 1824 Constitution, when the new republic adopted a federal system influenced partly by the United States. Mexico later used other official names during periods of centralist government, but the federal name was restored and remains the country’s constitutional designation.
A common mix-up is confusing Mexico’s official name with that of the United States. Both names contain “United States” in English translations, but Mexico is the country whose formal name is United Mexican States. Mexico is also the largest Spanish-speaking country by population and shares borders with the United States, Guatemala, and Belize.