The ordinary designations used by Texas people generally for the various sections of the state, such as East Texas, South Texas Plains, the Grand Prairies and Lampasas Cut Plain, the Lower Plains, the Edwards Plateau, the High Plains, the Coastal Plain, the Texas Prairies, and the Trans-Pecos, serve to point out the major natural regions of Texas. In their comparative aspects, each of these natural regions of the state partakes in a general way of characteristics of larger provinces of the United States. Thus, humid and forested East Texas is the westward prolongation from Louisiana of the Gulf timber belt, the latter being the counterpart of the Atlantic timber belt that stretches along the Atlantic coast south of the Potomac. The moderately humid Black Prairies region, the largest unit of the Southern Prairies, has many characteristics similar to those of the Mid-West or Corn Belt Prairies. The Edwards Plateau, the Lower Plains, the South Texas Plains, and the High Plains constitute a southern sector of the Great Plains, or the sub-humid portion of the United States. Trans-Pecos Texas is a part of the Cordilleran province and is a physiographic unit of the hot and dry southwest border zone, which crosses the continent, extending to the Pacific Ocean south of the transverse continental lineament. Although each of these Texas regions is in a general way the counterpart of larger provinces of the United States that extend into Texas and have their largest extents outside the state, yet the Texas regions have individual characteristics sufficiently distinct to rank them as separate natural regions. They are also are economic units, each as large as an ordinary state. Natural and political boundaries seldom coincide; therefore, the Texas regions extending to the boundaries of Texas also extend for some distance into the adjacent states without any pronounced break in physical features and characteristics.