Located on a glacial moraine that forms the beautiful, rolling hills of Henry County in north-central Illinois, the park sits astride a trail that led Native Americans from Lake Michigan to the confluence of the Mississippi and Rock rivers.Located off Illinois Route 78, Johnson-Sauk Trail is 6 miles south of Interstate 80 and 5 miles north of Kewanee. Originally known as the Henry County Conservation Area, a local newspaper invited the public to suggest names when the conservation area was going to be changed to a state park. Two names were popular with the public. One would name the park after State Senator Frank P. Johnson, a tireless worker on behalf of the park, while the second suggested Sauk Trail as a fitting name, for the Indian tribes most associated with the park when Europeans began settling the area.
The lake was one of a series of lakes considered for Illinois in 1944. After studying a number of sites, 369 acres of land known as Whiting's Woods were purchased. Actual construction of the lake didn't begin until 1949, and was halted soon after when engineers encountered unfavorable soil conditions. Work didn't get underway again until the summer of 1955, after advanced methods of dam construction were developed.