Granite City, Ill (KSDK) -- There were 57 vessels and 407 barges waiting to pass through the Port of St. Louis in the upper Mississippi River near Granite City as of Wednesday morning.
The Army Corps of Engineers closed Lock and Dam 27 because of a damaged protection cell that has hindered safe passage through the locks.
The number of vessels increased by one third and the number of barges doubled in the last 24 hours, according to the U.S. Coast Guard.
The amount of cargo held up by the closure is the equivalent to over 5,400 rail cars and over 23,600 large semis full of cargo.
Lock and Dam 27 is at mile-marker 185 just above St. Louis, and is the busiest lock and dam on the Mississippi River. It moves over 73 million tons of cargo each year.