All of Southeast Missouri and a good portion of NE Arkansas in th 1860s were covered by relatively shallow cypress and oak swamp. In 1903 a project called the Little River Drainage District was begun which effectively drained about 95% of the swamp area. This was accomplished by building what is called the Headwater Diversion Channel which diverts the water from the Little River and Little White Water River, Castor River, and Crooked Creek into the Mississppi River just south of Cape Girardeau MO. These rivers fed the swaps of Southeast Missouri and NE Arkansas. After diverting the rivers, a series of drainage ditches were dug running north and south in parrallel lines, there are over 60 of them. Ditch #1 or the Main floodway runs from just north of Chaffee Missouri, south through the entire bootheel of Missouri, exits Missouri east of Hornersville, and runs well into Arkansas as far south as below Osceola. It runs roughly parrallel to the original sttream bed of the Little River. The district exists today and still collects flood protection and property taxes from landowners in the district.
FWIW, just imagine the outcry from the EPA and environmentalists if a project of this magnitude was undertaken to drain several thousand square miles of virgin wetland today. Times do a change. Hope this helps you understand part of the geography. As an aside for those of you not from SE Missouri, Wappapello Lake, a Corp of Engineers flood control lake built in the 1930s, totally covers the civil war era town of Greenville MO. The New Greenville is located on US highway 67 some 20 odd miles north of the original town site. I've always wondered how much history was flooded without survey or thought, given the amount of comings and goings of forces of both sides through Greenville and the St. Francis River valley during the war.