218 A HISTORY OF AMERICA IN 100 MAPS
The Mississippi River is arguably the most important
waterway in the US, and certainly among the most
consequential in its history. The river drains
1.2 million square miles—40 percent of the
continental United States—into the Mississippi Delta.
The rich soils on either side of the river became the
heart of the slave plantation system in the 1850s, and
created enormous wealth at the height of the cotton
trade. Thereafter control of the river was central to
Union strategy in the Civil War, and it remained vital
to commerce well into the twentieth century. But the
river’s power was matched by its unpredictability,
which prompted the creation of the Mississippi River
Commission in 1879 both to improve navigation and
to control the recurrence of flooding.
Such efforts were repeatedly thwarted, most
importantly with the Great Flood of 1927. New
Orleans was largely spared when levees downriver
were destroyed to alleviate pressure on the city. The
hardest-hit areas of the delta were further north near
Greenville, Mississippi, where hundreds of thousands
of African Americans were displaced. The long-term
consequences were significant: within one year of
the flood, 50 percent of the black population of the
delta had moved out of the South into cities such as
Chicago and Detroit.
With the advent of the New Deal, more ambitious
public works—such as the Tennessee Valley Authority
(page 202)—encouraged engineers and scientists
to stabilize the banks and the flow of the Mississippi
River. Among the most creative and determined of
these men was Harold Norman Fisk, an irascible
geologist with the Louisiana Geological Survey who
convinced the commission to fund his comprehensive
study of the lower river in 1941.
Fisk argued that the river ought to be understood
as an evolving, dynamic entity given that it had
shifted its course over time. For two years he pushed
his colleagues relentlessly to reconstruct the
MAPPING THE MIGHTY MISSISSIPPI
Harold Norman Fisk, “Ancient
Courses [of the] Mississippi River
Meander Belt” (sheet 9), 1944
geological history of the river through fieldwork,
aerial photography, and archival research. The
photographs allowed him to search for long-
abandoned meanders and channels, and to see
layered patterns of soil, vegetation, and drainage.
Historical maps found in archives showed him
how the river had changed its course over the prior
century and a half.
The result was a landmark study that transformed
the way water engineers understood the river
itself. The report featured a series of elaborate and
beautifully executed maps that charted the wild
behavior of the river from the prehistoric era to the
present. With imaginative—even psychedelic—use
of color and shading, Fisk recreated the river’s history
in three dimensions: fifteen maps—stretching from
Cape Girardeau in Missouri down to Donaldsonville,
just above New Orleans—graphically illustrated the
patterns of flow and sedimentation that ignored
fixed riverbanks. Through these maps, scientists
could identify the formation of the meander belt
of the river about 6,000 years ago, and then trace
its subsequent evolution. With these images Fisk
made a contribution not just to geology and science,
but also to map design. His innovative approach to
capturing change over time has caught the attention
of mapmakers and graphic designers ever since.
It is worth noting that when Fisk completed the
maps during World War II they were printed by the
Army Map Service. The war revived transportation
on the river and intensified the federal government’s
attention to geological research. This section of the
map includes some of the area worst hit by the 1927
flood, illustrating its many diversions and cutoffs.
By examining the deep history of sedimentation,
Fisk was able to explain the rich alluvial plain that
extended into seven Southern states. And by studying
hydrographic surveys, he was able to document the
shifting banks and erosion that plagued the river.
Putting all these studies together, Fisk created a
crucial foundation for engineers to understand how
the river behaved, and how to address both the
incremental erosion and the more radical shifts
that led to the endemic flooding of the Lower
Mississippi Valley.