Great Falls of the Illinois River is a waterfall in LaSalle County, Illinois, in the Central Corn Belt Plains region. It lies about 0.5 miles south of Marseilles and roughly 35.3 miles southwest of Joliet as the crow flies.
Its height has not been recorded in the source data. By form it is a dam-created falls, where a man-made structure creates the drop.
The Central Corn Belt Plains are flat, intensively farmed former tallgrass prairie in Illinois and Indiana; waterfalls are rare and small, mostly along river bluffs.
LaSalle County holds 13 recorded waterfalls, and several are close by. Horseshoe Falls, a tiered waterfall, is about 11.6 miles away. Ottawa Canyon Falls, is about 12.4 miles away. Hennepin Canyon Falls, is about 12.9 miles away.
Great Falls of the Illinois River is located at 41.3235° N, 88.7084° W. The listing is based on the USGS Geographic Names Information System, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The position was verified on aerial imagery. Details on trails, parking and access have not been documented for this waterfall yet.