Freedom of movement under United States law in the context of "U.S. states"

In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it 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 share child custody.

State governments in the U.S. are allocated power by the people of each respective state through their individual state constitutions. All are grounded in republican principles (this being required by the federal constitution), and each provides for a government, consisting of three branches, each with separate and independent powers: executive, legislative, and judicial. 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 also create other local governments.

The Privileges and Immunities Clause (U.S. Constitution, Article IV, Section 2, Clause 1, also known as the Comity Clause) prevents a state of the United States from treating citizens of other states in a discriminatory manner. Additionally, a right of interstate travel is associated with the clause.