southwestern states State of Texas A state located in the South Central United States. The Rio Grande, Red River and Sabine River form natural state borders, Oklahoma on the north, Louisiana and Arkansas on the east, and the Mexican states of Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas to the south. LanguaL curation note: US FDA 1995 Code: US48 texas State of Texas A state located in the South Central United States. The Rio Grande, Red River and Sabine River form natural state borders, Oklahoma on the north, Louisiana and Arkansas on the east, and the Mexican states of Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas to the south. LanguaL curation note: US FDA 1995 Code: US48 texas