The North Fork Red River, sometimes called simply the "North Fork", is a tributary of the Red River of the South about 271 mi long, heading along the eastern Caprock Escarpment of the Llano Estacado about 11.4 mi southwest of Pampa, Texas. Rising in Gray County, Texas, it terminates at the confluence with Prairie Dog Town Fork of the Red River at the Te…The North Fork Red River, sometimes called simply the "North Fork", is a tributary of the Red River of the South about 271 mi long, heading along the eastern Caprock Escarpment of the Llano Estacado about 11.4 mi southwest of Pampa, Texas. Rising in Gray County, Texas, it terminates at the confluence with Prairie Dog Town Fork of the Red River at the Texas-Oklahoma border.