The United Mexican States is a federal republic composed of 32 Federal Entities: 31 states and Mexico City, an autonomous entity. According to the Constitution of 1917, the states of the federation are free and sovereign in all matters concerning their internal affairs. Each state has its own congress and constitution.
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 related to defense and security arrangements necessary to keep the border states secure in the event of an invasion.