A section of the swollen Mississippi River is open to shipping again after the US Coast Guard closed it to protect flood defences.
Barge traffic was halted at the port in Natchez, Mississippi, earlier on Tuesday, as ship wakes could increase pressure on the levees.
The river near Natchez is already one metre above the record set in 1937.
The BBC reports it is not expected to crest for several days, and it could take weeks for water levels to return to normal.
The Mississippi is a highway for barges carrying corn, soybeans and other crops brought down from the Ohio, Missouri and Mississippi river systems to the Gulf of Mexico.
The Army Corps of Engineers opened the Morganza Spillway at the weekend.
Nearly 5000 people had to leave their homes across Louisiana afterwards.