About This Place
Hennepin is a village on the Illinois River in Putnam County, Illinois, United States. The population was 707 at the 2000 census. It is the county seat of Putnam County.
Hennepin is part of the OttawaâStreator Micropolitan Statistical Area.
Hennepin is located at 41Â°15â²24â³N 89Â°19â²48â³W / 41.25667Â°N 89.33Â°W / 41.25667; -89.33 (41.256712, -89.329899).