southwestern states State of Oklahoma A state located in the South Central region and Southern Region of the United States of America. It is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, and on the south and near-west by Texas. LanguaL curation note: US FDA 1995 Code: US40 oklahoma State of Oklahoma A state located in the South Central region and Southern Region of the United States of America. It is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, and on the south and near-west by Texas. LanguaL curation note: US FDA 1995 Code: US40 oklahoma