The Marseilles Moraine, features from the last ice age that flattened most of Illinois, left a little bit of a divot where Illini State Park is located. This changing topography helped create scenic rapids along this section of the river, which you’ll have a hard time finding elsewhere along the river. The rapids were so strong that Illinois created a separate canal for shipping to Marseilles, which parallels the river. The area was home to a large-scale coal mining operation until World War II.

The land on which the park now sits was once a sprawling, swanky country club in the early 20th century. The Civilian Conservation Corps eventually turned this golf course into a park in the early 1930s, and Illini became an official state park in 1935. The old CCC camp buildings are still standing today, and Illini State Park campers can walk around these historic buildings as part of a small network of hiking trails throughout the park.