The United Mexican States (Spanish: Estados Unidos Mexicanos) is a federal republic composed of 32 federal entities: 31 states and one "federal district" (Mexico City).
According to the Constitution of 1917, the states of the federation are free and sovereign. Each state has its own congress and constitution, while the Federal District has only limited autonomy with a local Congress and government. The territory of the Federal District, commonly known and referred to as Mexico City, serves as the national capital.
The states of the Mexican Federation are free, sovereign, autonomous and independent of each other. They are free to govern themselves according to their own laws; each state has a constitution that cannot contradict the federal constitution, which covers issues of national competence. The states cannot make alliances with other states or any independent nation without the consent of the whole federation, except those of defense and security arrangements necessary to keep the border states secure in the event of an invasion. The political organization of each state is based on a separation of powers in a congressional system: legislative power is vested in a unicameral congress (the federal congress has two chambers); executive power is independent of the legislature and vested in a governor elected by universal suffrage; and judicial power is vested in a Superior Court of Justice. Since states have legal autonomy, each has its own civil and penal codes and judicial body.