Long recognized for its complex geological structure, unique flora and spectacular beauty, the Lake Michigan dunes area originally was, in the 1700s, part of the "Three Fires" of the Algonquin Nation: the Potawatomi, Chippewa and Ottawa. Prior to then, the area had been occupied by the Miami.
In the late 1600s, French explorers first visited the area as part of their survey of what was then known as the Northwest Territory. By the time Illinois became a state in 1818, the area was full of transient hunters and trappers. In 1836, a treaty was made with the local Native Americans, who were moved westward, and the area became part of Lake County.
Preservation efforts were considered as early as 1888, when Robert Douglas, a Waukegan nurseryman, and Jens Jensen, a famous landscape architect, discussed making it a regional park. With industry advancing from the south, sand mining ravaging the dunes and parts of the surrounding countryside succumbing to pasture and homesteads, legislative efforts to save the area finally began in the 1920s.
In 1948, the state acquired the first parcels of what is now Illinois Beach State Park. In 1950, the Illinois Dunes Preservation Society was established to protect the natural qualities of the area. Through its efforts and the efforts of the Department of Conservation, in 1964 the area south of Beach Road was dedicated as the first Illinois Nature Preserve. The northern unit, from the Commonwealth Edison power plant to the Wisconsin border, was acquired between 1971 and 1982.