A rare and spectacular set of thematic maps depicting historical changes in the channels of the Mississippi River, issued in 1938 by the Corps of Engineers and the Mississippi River Commission.
Those living on the banks of the Mississippi have always been blessed by its fertile alluvial plain and ready water access to much of the American interior and the Gulf of Mexico. But, at least since the advent of European settlement, they have also been vexed by its propensity to silt up, change course, and flood to catastrophic effect. Efforts to tame the river date back at least to 1718, when the French at New Orleans began construction of a levee to protect the city. By the time of the Great Mississippi Flood of 1927 there were more than 1500 miles of levee along the river, which at best failed to prevent the disaster and at worst exacerbated it.
A half-century earlier Congress had established the Mississippi River Commission, charging it with developing and implementing plans to control the river’s channel, in order to improve navigation, facilitate commerce and prevent flooding. After the 1927 flood, The Flood Control Act of 1928 assigned the Commission vast new resources and responsibilities, including oversight of the entire tributary system of the river. To guide improvements in flood control the Act provided, among other things, for a survey of the river between Baton Rouge and Cairo, Illinois, where the Ohio merges with the Mississippi.
That survey, conducted in 1930-32, provided the base for an extraordinary set of twelve thematic maps—ten of which are present here, with sheets 9 and 10 in facsimile–documenting historic changes in the channel of the Mississippi. Each is a map in itself, including title, legend, imprint and neat line, but if placed end-to-end the full set of twelve would form a 50-foot strip map of the river from Cape Girardeau, Missouri 50 miles upstream from Cairo, to St. James Parish, some 40 miles downstream from Baton Rouge. The base maps, printed in black, are taken from the preliminary topographic quads of the 1930-32 survey. Superimposed in four colors are the course of the river at roughly half-century intervals: blue for Lieutenant Ross’s survey of 1765, red for the General Land Office surveys of 1820-1830, green for the Mississippi River Commission survey of 1881-83, and yellow for the Commission’s survey of 1930-32 (Ross was a member of the British 34th Regiment, sent in 1765 on an expedition from Mobile to conciliate the tribes of the Illinois country, then in revolt.)
With their considerable size and serpentine, intertwining bands of color, the maps are visually striking. Beyond their visual appeal, the implications are shocking, at least for those accustomed to think of geography as fixed, or at most changing over a time scale of millennia. The maps make immediately evident how the Mississippi’s course has changed in places by as much as several miles, sometimes in as little as half a century.
These 1938 maps paved the way for an even more ambitious effort by the Mississippi River Commission, the 1944 Geological Investigation of the Alluvial Valley of the Lower Mississippi River. That work included a 15-sheet map, Ancient Courses: Mississippi River Meander Belt, which also used color to trace the river’s changing channel, but at no fewer than 30 successive time periods.
Given the huge population and the economic value of the agriculture and industry in the river’s floodplain, the Commission’s maps were a powerful call to action. Indeed, over the following decades billions were spent strengthening levees and constructing floodways to divert floodwaters, though all to little effect. Massive floods in 1973 and again in 1993 demonstrated that flood-control measures only increased the likelihood and severity of flooding.
In all, a spectacular set of maps of the Mississippi, both intrinsically interesting and significant for their influence on Federal attempts to control an ultimately uncontrollable force of nature.
References
OCLC 21695002 et al, giving fewer than 20 institutional holdings (Feb. 2022). Background from Hsieh Wen Shen and Eric Larsen, “Migration of the Mississippi River”, Berkeley: Department of Civil Engineering, University of California, July 1988; Alexis Madrigal, “What We’ve Done to the Mississippi River: An Explainer”, The Atlantic (May 19, 2011), accessed Feb. 2022 at theatlantic.com. See also Erin Kelly, “The Meandering Mississippi”, posted June 2, 2016 on the Library of Congress web site.