Founded in 1971 as Railsplitter State Park, it was renamed in 1995 in honor of Edward R. Madigan, a former member of the U.S. House of Representatives from the town of Lincoln and a U.S. Secretary of Agriculture.

One of the park's primary assets is a 2.5-mile (4 km) section of Salt Creek, a major tributary of central Illinois' Sangamon River.

The Madigan Salt Creek bottomlands contain one of Illinois's largest American sycamore trees.

Outside the creek bed, the conservation area contains several groves of white oak and hickory, typical of central Illinois.

Old U.S. Highway 66, now Interstate Business 55, passes through the Madigan State Fish and Wildlife Area.