Taming the Wild River

Americans long sought to improve the Upper Mississippi River for commercial navigation after recognizing its potential as a transportation route. In 1878, Congress authorized the U.S. Army Corps of Engineers to create a continuous four-foot channel from St. Paul to the mouth of the Ohio River at Cairo, Illinois, leading the Corps to build hundreds of wing dams, long rock piers extending from shore, and closing dams running from shore to island or island to island. In 1907, the minimum channel depth was increased to six feet, and by 1930, when Congress authorized a nine-foot channel, more than 1,000 wing and closing dams had been installed. Lock and Dam No. 7, built between 1934 and 1937, was part of a system of 29 locks and dams between Minneapolis and St. Louis designed to keep the main channel at least nine feet deep, effectively transforming the once-wild river into a long stairway. These changes aided commercial navigation, raising river commerce from less than one million tons annually in the mid-1920s to more than 70 million tons a year, but they also altered the river's ecology by eliminating many side channels and backwaters that had provided wildlife habitat. Although the modern lock and dam system submerged most of the older dams and reflooded backwater areas, the river's restricted movement has caused many of those areas to fill gradually with sediment. Over time, many kinds of boats traveled this part of the Mississippi, including birchbark canoes, keelboats, ferryboats, steamboats, and barges.

Minnesota · United States