<P> The Red River , or sometimes the Red River of the South , is a major river in the southern United States of America . The river was named for the red - bed country of its watershed . It is one of several rivers with that name . Although it was once a tributary of the Mississippi River , the Red River is now a tributary of the Atchafalaya River , a distributary of the Mississippi that flows separately into the Gulf of Mexico . It is connected to the Mississippi River by the Old River Control Structure . </P>
why is the red river named the red river
named for the red - bed country of its watershed