Southwest Oklahoma is a geographical name for the southwest portion of the state of Oklahoma , largely flat and dry , southwest Oklahoma is typical of the Great Plains region of the United States . Southwest Oklahoma is a geographical name for the southwest portion of the state of Oklahoma , typically considered to be south of the Canadian River , extending eastward from the Texas border to a line roughly from Weatherford , to Anadarko , to Duncan . The region has an official designation created for tourism purposes , Great Plains Country .