Red River

Also called �Red River Of The South, � navigable river rising in the high plains of eastern New Mexico, U.S., and flowing southeast across Texas and Louisiana to a point northwest of Baton Rouge, where it enters the Atchafalaya River (q.v.), which flows south to Atchafalaya Bay and the Gulf of Mexico. Until the mid-20th century, the Red River contributed flow to both the Atchafalaya and, via the Old River, the Mississippi.