In the United States, a state is a constituent political entity, of which there are currently 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory and shares its sovereignty with the federal government. Due to this shared sovereignty, Americans are citizens both of the federal republic and of the state in which they reside. State citizenship and residency are flexible, and no government approval is required to move between states, except for persons restricted by certain types of court orders (such as paroled convicts and children of divorced spouses who are sharing custody).
States are divided into counties or county-equivalents, which may be assigned some local governmental authority but are not sovereign. County or county-equivalent structure varies widely by state, and states may also create other local governments. State governments are allocated power by the people (of each respective state) through their individual constitutions. All are grounded in republican principles, and each provides for a government, consisting of three branches, each with separate and independent powers: executive, legislative, and judicial.