Railroad companies could see more demand with more reports now out that the low level of the Mississippi River will limit the ability of barges to run up and down the river. The biggest danger is that a 200-mile stretch of the mighty river between St. Louis, Missouri and Cairo, Illinois could be effectively closed. Waiting in the wings: $CSX , $RA , $CNI , $PWX , $GWR , $CP , $NSC , $KSU , $UNP