In this series, the curatorial team presents one work from the Meural art library we find essential. (See all installments.)

Between 1941 and 1944, as Allied troops fought to reclaim large swaths of occupied Europe, Harold Fisk, a geology professor from Louisiana State University, was engaged in a very different kind of battle: to map the history—past and present—of the mighty, meandering Mississippi River. His resulting report for the US Army Corps of Engineers had an unpromising title—Geological Investigation of the Alluvial Valley of the Lower Mississippi River—but contained some of the most beautiful, intricate hand-drawn maps I’ve ever encountered.

All rivers search for the path of least resistance, and Fisk’s meticulous contour maps reveal the Mississippi’s changing shape and nature—color-coded ghost trails that chart the complex twists and turns that the world’s fifth longest river took before finding smoother passage. Pale blue shows its 1765 course, brick red is 1820, and bright green 1880.

How did Fisk do it? A combination of geological analysis and academic interpretation. Over 3 years, Fisk and his small team, collected around 16,000 borings of soil, sand, and gravel from along 600 miles of the Lower Mississippi. And by evaluating them in tandem with aerial photographs, they were able to intuit the river’s past contortions, and tell a magnificent visual history of one of America’s major arteries.

— Poppy Simpson, Head of Curation