Louisiana is a state in the Deep South and South Central regions of the United States. It is bordered by Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25th in population, with roughly 4.6 million residents. Reflecting its French heritage, Louisiana is the only U.S. state with political subdivisions termed parishes, which are equivalent to counties, making it one of only two U.S. states not subdivided into counties. Baton Rouge is the state's capital, and New Orleans, a French Louisiana region, is its most populous city with a population of about 363,000 people. Louisiana has a coastline with the Gulf of Mexico to the south; a large part of its eastern boundary is demarcated by the Mississippi River; and the mouth of the Mississippi or delta defines much of its lower topography.