1870s: Construction of the Locks and Dams

The importance of the Illinois River for the defense of the country becomes evident during the Civil War. There are concerns that British warships on the Great Lakes will come to the aid of the Confederacy. The federal government is therefore pressured to enlarge the I & M Canal and make the Illinois River navigable for larger boats.

Other military concerns exist, as Brevet Major General J.H. Wilson writes in 1867:

The recent confederation of the British American provinces shows the anxiety felt by the English governments in this behalf and must be regarded as a movement in hostility to the people and institutions of the United States. The government must either connect the lakes and the Mississippi River by a canal of sufficient capacity to accommodate gunboats suitable for service on the lakes, or prepare for annexation or conquest of Canada. (Lamb 2001).

Wilson proposes a depth of seven feet for both the canal and river, which would require six locks and dams south of La Salle.

Wilson’s interest in improving navigation is broader than the defense of this country, reflecting his belief in the nation’s Manifest Destiny. In 1867 he again writes:

To the people of our race nothing is more inexorable than a commercial necessity, nor argument is so potent as that based upon physical facts, and no ethics so readily understood as those which relate to the national welfare, when our people have been brought to thoroughly understands this necessity...they will not be over nice in regard to the territorial rights of those who bar the door to the eastern market, but will demand the extension of our borders so that their commerce may find is way ‘unvexed to the sea’ by the St. Lawrence, as it now does by the Mississippi (Lamb 2001).

When the debt is retired on the I & M Canal in 1870, the state begins making changes that further affect the flow of the river. Two locks are built, one at Henry and one at Cooper’s Creek, to increase the depth of the river and to clear the wooded areas on the banks. The low flow is doubled by 1880, with further changes to come.