The State of Mexico, officially the Free and Sovereign State of Mexico, is one of the 31 states which, with the Federal District, comprise the 32 federal entities of the United Mexican States. It is the most populous, as well as the densest populated. It is divided into 125 municipalities and its capital city is Toluca de Lerdo.
The State of Mexico is often abbreviated to "Edomex" from Estado de México in Spanish. It is located in South-Central Mexico. It is bordered by the states of Querétaro and Hidalgo to the north, Morelos and Guerrero to the south, Michoacán to the west, Tlaxcala and Puebla to the east and surrounds the Federal District.
The state’s origins are in the territory of the extinct Aztec Empire, which remained a political division of the New Spain during the Spanish colonial period. After Independence, Mexico City was chosen as the capital of the new nation; its territory was separated out of the state. Years later, parts of the state were broken off to form the states of Hidalgo, Guerrero and Morelos. These territorial separations have left the state with the size and shape it has today, with the Toluca Valley to the west of Mexico City and a panhandle that extends around the north and east of this entity.
The state name is simply México according to the 1917 Constitution of the United Mexican States, but to distinguish it from both the city and the country it is most often called Estado de México. The demonym used to refer to people and things from the state is mexiquense, distinct from mexicano ("Mexican"), that describes the people or things from the country as a whole.