It is formed near Simmesport at the confluence of the Red River with the Mississippi, where the Mississippi connects to the Red by the 7 mi (11 km) canalized Old River. It receives the water of the Red as well as part of the water of the Mississippi, which itself continues in its main channel to the southeast. It meanders south as a channel of the Mississippi, through extensive levees and floodways, past Morgan City, and empties into the Gulf of Mexico in Atchafalaya Bay approximately 15 mi (25 km) south of Morgan City. The river is forming a new delta in the bay.