Department of Transportation.
The Loess Hills of western Iowa are truly an American treasure. The outstanding prairie and forest-covered bluffs draw people from around the world. With an impressive network of state parks, private preserves, and national landmarks, travelers to the byway have a myriad of opportunities to see and explore this natural wonder. The unique land formation of windblown silt called “loess” extends nearly 200 miles in a narrow band adjacent to the Missouri River Valley. Although deposits of loess are found across the world, nowhere but China are those deposits higher than they are in Iowa. The Loess Hills encompasses over 640,000 acres of land with over 10,000 acres designated as a “Loess Hills National Natural Landmark.” See many archeological sites where pottery, tools, and other artifacts have been left behind by the ancient Mill Creek and Glenwood cultures, who inhabited the area between 1000-1300 AD. In 2008, the State Archaeologist recorded over 1,500 inventoried archaeological sites in the Loess Hills. The Glenwood culture near the southern end of the Loess Hills has many 800-year-old earthlodges, and to the north is a small cluster of Mill Creek culture sites around Sioux City.