This article originally appeared on NPR.

Sixty percent of the nation's agricultural exports move by barge up and down the Mississippi River system, as do billions of dollars' worth of petroleum, coal, steel and other commodities. It's a critical lifeline for the nation's economy, but one not without problems.

One of the problems is infrastructure, like locks and dams, canal walls, flood walls and levees, says Del Wilkins with the Canal Barge Co., which operates barges and tows all throughout the Mississippi River system. "Infrastructure is old, and it's crumbling," he says.

Wilkins says one barge can carry the freight equivalent of 144 trucks or 46 rail cars, yet the nation's water infrastructure, he says, is generally left out of the transportation funding conversation in Washington — until there's a crisis. And over the past two years, the Mississippi River has endured two near-catastrophes.

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