 After new manufacturing facilities opened on the Calumet River in the southern portion of Chicago, shipping traffic on the Chicago River fell dramatically.By the mid-1920s, the Department of Public Works had floated a proposal to replace the moving bridges with fixed spans through a ten-year period from 1925–1935, citing high maintenance costs.The proposal was not acted upon, partially due to opposition by the Army Corps of Engineers; however, except for a brief resurgence in traffic during World War II, shipping volume remained low.