In the 1850s, Chicago’s harbor emerged as a critical link between the waterways of the Great Lakes, including the Erie Canal, and the new railroads leading from riverside docks and piers (as shown on this map) to the interior of the country. Repeated attempts to keep the river and harbor clear of sediment had had only temporary effect. In April 1854, the government brought Lieutenant Colonel James Duncan Graham (1799-1865), a member of the Army Corps of Engineers, to Chicago in April 1854 to direct more comprehensive improvements. The improvements cost $200,000, four times the amount spent on previous improvements. Graham’s 1858 map of the Chicago Harbor and Bar records the data from soundings taken by his engineers in order to determine the water depth and hence the silt accumulation on the harbor’s floor. Detailed notes on the map describe the process he used to calculate the precise latitude and longitude of the site. This enabled him to pinpoint the underwater locations needing to be dredged. The detailed three-dimensional visualization of the river mouth and adjacent lakeshore offers a clear picture of how the prevailing southward flow of the lakeshore current and consequent drift of lake sand constantly pushed the natural flow of the river towards the south. In addition to constant dredging, the construction and continued extension of a pier outward into the lake following the line of the north bank of the river, restrained, but did not stop these natural forces. In addition to noting depths, the map shows how sediments building up on the north side of the pier had extended the shore of the lake outward (eastward) by nearly a quarter of a mile since the 1820s.
Hill, Libby. The Chicago River: A Natural and Unnatural History. Chicago: Lake Claremont Press, 2000.
Solzman, David M. The Chicago River: An Illustrated History and Guide to the River and Its Waterway, 2nd ed. Chicago: University of Chicago Press, 2006.
J.D. Graham, Chicago Harbor & Bar, Illinois (New York: Lithographers of J. Bien, 1858). The Newberry Library, map6F G4104.C6:2C5 1858 .U5 (NLO)