main tributary of the Canadian River in the south-central United States. It rises in a high plateau in Union county, New Mexico, and flows east through the Texas and Oklahoma panhandles past Oklahoma City, joining the Canadian River in Eufaula Reservoir, below Eufaula, Okla. The North Canadian River is 800 miles (1,287 km) long and drains 14,290 square miles (37,011 square km). Above the mouth of Wolf Creek, one of its tributaries, the North Canadian is also known as Beaver River. Irrigation lakes are impounded by Canton Dam (1948) on the main stream in Oklahoma and by Fort Supply Dam (1942) on Wolf Creek.