Hennepin is located along the banks of the Illinois River in north central Illinois in Putnam County, (of which it is the county seat), southwest of La Salle along Highway 26. It is named for Louis Hennepin, an explorer under Sieur de La Salle's command in the late 1600's.
The Hennepin Canal, a man-made channel which connects the Illinois with the Rock River and eventually with the Mississippi River, was 155 miles long and rose nearly 200 feet at a point near Wyanet via 21 locks. Construction took place between 1890 and 1907. As the railroads were developed, however, they claimed quicker and more efficient transportation and canal traffic became obsolete. The canal is now a part of Hennepin Canal Parkway State Park with its headquarters in Sheffield.