United Mexican StatesThe alternative translation Mexican United States is also, but not often, used.[1] (Spanish: Estados Unidos Mexicanos (help·info) ), or commonly Mexico (IPA: /ˈmɛksɪkoʊ/) (Spanish: México (help·info) IPA: [ˈmexiko]), is a federal constitutiona l republic in North America. It is bounded on the north by the United States; on the south and west by the North Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of Mexico.Merriam-Webster's Geographical Dictionary, 3rd ed. Springfield, MA: Merriam-Webster, Inc.; p. 733 "Mexico". The Columbia Encyclopedia, 6th ed. 2001–6. New York: Columbia University Press. The United Mexican States is a federation comprising thirty-one states and a federal district, the capital Mexico City, which is one of the world's most populous cities.