Chicago River Mouth

The harbor lock at the mouth of the Chicago River is one of many changes people have made to the river and lake since the early 1800s. Even before Chicago became a city, soldiers began removing sandbars near where the lock now stands to make it easier to ship supplies to Fort Dearborn. Over the centuries, the river has been expanded, straightened, linked to nearby waterways, and reversed to flow away from Lake Michigan. Many of these changes have been recognized as marvels of civil engineering.