Visitors look at displays about the U.S. Army Corps of Engineers Nashville District, Great Lakes and Ohio River Division and Tennessee Valley Authority onboard the Motor Vessel Mississippi during a public tour of the vessel docked at Ross's Landing in Chattanooga, Tenn., Aug. 7, 2015. The M/V Mississippi spends more than 90 percent of its time as a working towboat, moving barges, equipment and supplies on the lower Mississippi River. The M/V Mississippi, built in 1993 by Halter Marine, is the fifth Army Corps of Engineers towboat to bear the name. It is the largest diesel towboat in the United States at 241-feet long, 58-feet wide and five stories high. Three 2,100-horsepower diesel engines power the vessel. (USACE photo by Leon Roberts)