. "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.Anchored by Lawton, its largest city, Southwest Oklahoma's other important urban centers include Elk City, Clinton, Weatherford, Walters, Altus, and Duncan."@en . .