This region evolved out of the archaic southwest, which originally was literally the western U.S. South. The states of Arkansas, Louisiana, Oklahoma, and Texas are considered the “core” of the region. Alabama, Mississippi, Tennessee and Kentucky are also frequently listed under the same heading. At the highest extent, Kansas, Missouri, and New Mexico may be included by some sources.
The climate varies from the semi-tropical in the Mississippi Delta, South Louisiana, and Southeast Texas, to the dry Chihuahuan desert in West Texas and southern New Mexico. The southeastern portions include the Appalachian Mountains in Alabama and Tennessee and the Piney Woods of East Texas, Louisiana, and southern Arkansas and the Mississippi Delta. Large portion of the northeastern quarter of the region is mountainous, with the Ozark and Ouachita Mountains of Arkansas and eastern Oklahoma. The northwest quarter of the region is dominated by the Great Plains which become progressively drier west of 100° W, forming the North American Llano. The southwestern portions border the Rio Grande, and are generally drier than other areas of the South Central United States, Central Texas having the most annual precipitation.
Texas is the largest South Central state by both area and population—even when New Mexico is included. Texas is still home to over half the region’s population. The largest city in the region, Houston, is located in Texas. New Orleans was tied with Oklahoma City but, after Hurricane Katrina, the population of the New Orleans metro area has declined to approximately 900,000. However a survey shows that the population has bounced back to almost 1.2 million as of April 2007).