A secondary goal was to replace the shallow and narrow Illinois and Michigan Canal (I&M), which had originally connected Lake Michigan with the Mississippi starting in 1848. As part of the construction of the new canal, the entire route was built to allow much larger ships to navigate it. It is wide and deep, over three times the size of the I&M. The I&M became a secondary route with the new canal's opening and was shut down entirely with the creation of the Illinois Waterway network in 1933.