A truck drives on top of a levee that protects a soybean field in New Madrid County, Mo., when the Mississippi River floods. Kristofor Husted/KBIA hide caption

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A levee protects a home surrounded by floodwater from the Yazoo River near Vicksburg, Miss., May 18, 2011. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images

A levee protects a home surrounded by floodwater from the Yazoo River near Vicksburg, Mississippi on May 18, 2011. Scott Olson/Getty Images hide caption

itoggle caption Scott Olson/Getty Images

Water from the Mississippi River rushes out of open bays on the Morganza Spillway and into a pasture in Morganza, La., on Monday, May 16, 2011. Patrick Semansky/AP hide caption

itoggle caption Patrick Semansky/AP