The largest U.S. Census geographical division in the South is the South Atlantic. The South Atlantic division comprises the District of Columbia and the states of Delaware, Maryland, Virginia, West Virginia, North Carolina, South Carolina, Georgia and Florida. The largest city in the South Atlantic region is Jacksonville, Florida, with a 2010 U.S. Census population of 821,784. The South Atlantic's largest state, in terms of total area, is Florida, which has over 58,560 square miles of land mass. The eastern border of the South Atlantic division is on the edge of the Atlantic Ocean.
The East South Central region has four states: Kentucky, Tennessee, Alabama and Mississippi. Its largest city, Memphis, Tennessee, is also one of the division's westernmost urban areas. As of April 2011, Memphis had a population of 646,889. Alabama is the largest state in the East South Central region with a total area of 52,423 square miles. The longest river in the United States, the Mississippi River, makes up most of the western border for the East South Central division.
The remaining states in the South region are in the West South Central division. All of these states -- Louisiana, Arkansas, Oklahoma and Texas -- are west of the Mississippi River. The largest state in the continental United States and thus of the West South Central division is Texas. Texas has a total area of 268,581 square miles; this includes land areas and bodies of water. The Lone Star State is also home to the three largest cities in the West South Central division: Houston, San Antonio and Dallas. All three of these cities have over one million residents. The southern edge of West South Central is adjacent to the Gulf of Mexico and the United States--Mexico border.
Some of the South region's states have created unofficial geographical borders for cultural and historical reasons. The Carolinas region of the South includes North Carolina and South Carolina; this term dates back to America's Colonial era. Texas, Arkansas, Louisiana, Mississippi, Alabama, Georgia and the Carolinas make up the Bible Belt, due to the high concentration of Protestant Christians who live in these states. The Tennessee Valley makes up most of Tennessee and the northern regions of Alabama and Georgia; this geographic region consists of the river basin area surrounding the Tennessee River.
