Louisiana is a state in the Deep South region of the southeastern United States. It is the 31st most extensive and the 25th most populous of the 50 United States. Louisiana is bordered by Arkansas to the north, Mississippi to the east, the Gulf of Mexico to the south, and Texas to the west. A large part of its eastern boundary is demarcated by the Mississippi River. Louisiana is the only U.S. state with political subdivisions termed parishes, which are equivalent to counties. The state's capital is Baton Rouge, and its largest city is New Orleans.