The Canadian River, the largest tributary of the Arkansas River, rises in the Sangre de Cristo Mountains in southern Las Animas County, Colorado, near Raton Pass and the boundary line with New Mexico. It flows south and southeastward, separating the Llano Estacado from the northern High Plains. It is roughly 760 miles long; a stretch of about 190 miles is in Texas.
The river is dammed to form the Conchas and Ute reservoirs in northeastern New Mexico before it enters Texas at about the midpoint of the western boundary of Oldham County. The Canadian crosses the Panhandle, flowing eastward and northeastward with most of the river's course across the Panhandle passes through a gorge 500 to 800 feet below the plateau. After crossing the state line back into Oklahoma, the Canadian River flows generally southeastward to its mouth on the Arkansas River.