Every fall, during low-water time on the Mississippi River, a crew of about 300 men and women turns out to resume one of the longest-running and most important construction projects of the U.S. Army Corps of Engineers—the placement of articulated concrete mattresses along the levees to prevent scour and protect communities.

The Corps was given the armor-the-levees mission in 1885, although its armoring work predates that. Now, the “construction phase” is almost done, with about 1,000 miles of levee, from Cairo, Ill., to Head of Passes, at the mouth of the river, protected.