This Dec. 5, 2012 photo provided by The United States Coast Guard shows barges passing in tight quarters due to low water levels as they navigate the Mississippi River near St. Louis. (AP Photo/United States Coast Guard, Colby Buchanan)
Excerpts from National Geographic News:
The middle Mississippi—the 200-mile (322-kilometer) stretch from St. Louis to Cairo, Illinois—is experiencing drought conditions unrivaled in the last 50 years.
The result is that transport along the Mississippi is down dramatically. Barges have had to lighten their loads considerably to avoid bottoming out. Right now barges on the middle Mississippi can only afford to sink 9 feet (2.7 meters) into the water, some only 8 feet (2.4 meters). They usually run 12 feet (3.7 meters) deep, more laden with goods to get them to market faster and cheaper.
One of the effects is that farmers on the middle Mississippi, the drought-strapped area, are paying a dollar more to ship each bushel of crops than are farmers on the lower Mississippi, who can fully load barges before sending them down the river. … Sixty percent of farm exports for the entire U.S.—largely corn and soybeans—move along the Mississippi.