For the current entity named United Mexican States, see Mexico.

The First Federal Republic was a period in Mexican history corresponding to the first time in which both, republic and federation were established as form of government in the Mexican nation. Officially the United Mexican States (, ),, it was bordered on the north by the United States and Oregon Country; on the south and west by the Pacific Ocean; on the southeast by Federal Republic of Central America, and the Caribbean Sea; and on the east by the Gulf of Mexico.