107 The Agricultural Economy of the American Bottoms 
a height of thirty feet on the river gauge at St. Louis.! It has been 
estimated that only about ten per cent of the American Bottoms is above 
a flood stage of thirty-five feet.2. The somewhat precarious position of 
the flood plain is shown by the fact that the 1844 flood, the highest 
flood of the upper Mississippi River ever recorded, reached an elevation 
of 41.3 feet above zero on the St. Louis gauge. 
The surface waters drained across the flood plain include water 
emerging from the upland in addition to water originating on the fl 
plain. The American Bottoms, aside from small areas draining directly 
into the Mississippi River, is divided among the basins of Wood River, 
Cahokia Creek, and Prairie du Pont Creek (Fig 18). The Wood River 
basin includes three square miles of flood plain, the Cahokia Creek 
basin one hundred square miles, and the Prairie du Pont Creek basin 
thirty-six square miles. In the absence of sharp divides on the flood 
plain, these figures are only approximately correct. The combined 
upland areas of the three drainage basins are practically four times as 
large as the combined lowland areas. 
Wood River drains a few square miles of lowland located to the west 
of the Big Four Railroad and adjoining Alton (Fig. 18). The lowland 
area drained by Cahokia Creek is bounded on the west by the Big 
Four Railroad extending from East St. Louis northward to the blufis 
near Upper Alton, on the south by the Pennsylvania Railroad extending 
from East St. Louis to the bluffs at Caseyville, and on the north and 
east by the bluffs. With the exception of a narrow strip of land along 
the Mississippi River, the Prairie du Pont Creek basin includes all the 
American Bottoms to the south of the low divide on which the Penn- 
sylvania Railroad is located. 
‘Zero on the gauge is 379.796 feet above mean sea level. 
*1. Bowman, and C. A. Reeds, Water Resources of the East St. Louis District (Urbana: 
University of Illinois, 1907,) St 
‘Unpublished chart, Engineers Office, Department of War, St. Louis, 1937. 
J ‘Edwin G. Helm, “The Levee and Drainage Problem of the American Bottoms 
ournal Association of Engineering Societies, XX XV (1905), 92-93. 
a ee ee re pans eee! Ce 
