Split Rock Creek State Park in southwestern Minnesota near Ihlen was developed around a lake created in 1938, when the Works Progress Administration built a Sioux Quartzite dam to provide water recreation in a region with few natural lakes. The same project also produced the Split Rock Creek Bridge, a Sioux quartzite structure carrying County Road 54 and later recognized on the National Register of Historic Places. The park takes its name from Split Rock Creek, once known as Eminija, a 55-mile stream that begins near Ihlen, flows into South Dakota, passes several parks and landmarks, and eventually joins the Big Sioux River east of Sioux Falls.