In this Dec. 18, 2012 photograph, the sun sets on the river vessel influenced Lower Mississippi River Museum in Vicksburg, Miss. The museum provides visitors with a extensive look at life surrounding the Mississippi River through several centuries by way of its interactive and static displays. Visitors also have the opportunity to tour the Motor Vessel Mississippi IV exhibit and see how crews worked and lived on the towboats used by the U.S. Army Corps of Engineers. (AP Photo/Rogelio V. Solis)

In this Dec. 18, 2012 photograph scale examples of the various types of river vessel used on the Mississippi River, are on display at the Lower Mississippi River Museum in Vicksburg, Miss. The museum provides visitors with a extensive look at life surrounding the Mississippi River through several centuries by way of its interactive and static displays. Visitors also have the opportunity to tour the Motor Vessel Mississippi IV exhibit and see how crews worked and lived on the towboats used by the U.S. Army Corps of Engineers. (AP Photo/Rogelio V. Solis)

In this Dec. 18, 2012 photograph, visitors to the Lower Mississippi River Museum in Vicksburg, Miss., have the opportunity to sit at a captain's chair in the pilot house of the Motor Vessel Mississippi IV, a U.S. Army Corps of Engineers towboat that floated up and down the Mississippi River. The museum provides visitors with a extensive look at life surrounding the Mississippi River through several centuries by way of its interactive and static displays, while the Motor Vessel Mississippi IV exhibits show how crews worked and lived on the towboats. (AP Photo/Rogelio V. Solis)

In this Dec. 18, 2012 photograph, the U.S. Army Corps of Engineers towboat and inspection vessel, Motor Vessel Mississippi IV, sits in a permanent dry dock as part of the Lower Mississippi River Museum in Vicksburg, Miss. The museum provides visitors with a extensive look at life surrounding the Mississippi River through several centuries by way of its interactive and static displays. Visitors also have the opportunity to tour aboard the vessel and see how crews worked and lived on the towboats used by the Corps of Engineers. (AP Photo/Rogelio V. Solis)

In this Dec. 18, 2012 photograph, visitors can see a book of river maps and charts in the pilot house of the Motor Vessel Mississippi IV at the Lower Mississippi River Museum in Vicksburg, Miss. The museum provides visitors with a extensive look at life surrounding the Mississippi River through several centuries by way of its interactive and static displays. (AP Photo/Rogelio V. Solis)