How do locks and dams make the upper Mississippi River navigable to Minneapolis and St. Paul?

To make the upper Mississippi River navigable for commercial traffic, 29 locks and dams were constructed along the river. These structures allow vessels to navigate the waterway by creating a series of pools that maintain a consistent, navigable channel depth of 9 feet (2.75 metres) as far upstream as Minneapolis–St. Paul.1

By regulating water levels, these locks and dams enable towboats to transport large, rigid platforms of barges through sections of the river that would otherwise be too shallow or difficult to navigate. This infrastructure is part of a broader, long-term navigation-improvement program overseen by the Mississippi River Commission, which has profoundly reshaped the river to support modern commercial activity.1