List of Mexican states by date of statehood
This is a list of Mexican States by date of statehood, that is, the date when each Mexican State was accepted by Congress of the Union as a free and sovereign state of the Mexican Union. The effective independence of Mexico reached on September 27, 1821, does not meant the independence of the states, because Mexico was the only Latin American country which became independent from Spain as a monarchy. After the fall of the Mexican Empire, the Federal Republic was established on July 12, 1823. Although 18 of the 19 founder  states can be considered official members of the federation since the enactment of the "Constitutive Act of the Mexican Federation" on January 31, 1824; eleven of them were ratified as states before the enactment and some of the others were included as three states (the internal States of North, Western and Eastern). Tamaulipas, Tabasco and Chiapas were ratified after the enactment of the act. All the later admission dates were set by law or decree of congress, except for Chiapas, whose admission was determined by its own people in a referendum. This list does not account the secession of several  states during the establishment of the Centralist Republic and the territorial changes made during the civil and foreign wars.