South Texas Plains GuideTexas's southern region is, for the most part, a forbidding desert area. A borderland with nearby Mexico, it acts as a gateway for those coming North and those going South. HotelsFind hotels in San Antonio, Castroville, Laredo, Del Rio, Eagle Pass and more. San AntonioSan Antonio is the second largest city in the state of Texas and 7th largest in the United States. CastrovilleCastroville is a city in the South Texas Plains. Castroville is known as the Little Alsace of Texas, because its founder brought in a large group of settlers from Alsace in the 1840s. LaredoThe twin cities of Laredo, Texas and Nuevo Laredo, Mexico, which celebrated their 250th anniversary in 2005, are situated on the banks of the Rio Grande. Del RioDel Rio is a city in the South Texas Plains, across the Rio Grande from Ciudad Acuña in Mexico. Eagle PassEagle Pass is a city on the South Texas Plains. It is just across the river from the slightly larger city of Piedras Negras in the Mexican state of Coahuila. Duval CountyDuval County is located in the South Texas Plains, roughly an hour west of Corpus Christi and an hour east of Laredo. Carrizo SpringsCarrizo Springs is a city on the South Texas Plains. Natural Bridge CavernsThe Natural Bridge Caverns are in Texas, United States of America. Just a few miles from San Antonio, Texas are Natural Bridge Caverns, which are the largest commercial cavern in the state of Texas. MissionMission is a city in southern Texas.