Mill Creek

by Rich Fishel 
© Copyright 1996 The University of Iowa. All rights reserved.

From A.D. 1000-1200 northwest Iowa was home to a highly distinctive and short-lived group of inhabitants whose arrival, existence, and disappearance has puzzled researchers for nearly 100 years. These people, now known as the Mill Creek culture, followed a way of life completely different from those before them. The uniqueness of this culture has created an interest unparalleled among many Iowa archaeologists. 

The Mill Creek culture is part of a larger group of horticultural villages that start to appear around A.D. 1000 near the Missouri River from northwest Iowa to central South Dakota. These groups have been labeled by archaeologists as the Initial Variant of the Middle Missouri tradition. The 35 known Mill Creek villages cluster in two distinct areas in northwest Iowa: along the Little Sioux River and its three tributaries (Brooke Creek, Mill Creek, and Waterman Creek) and along the Big Sioux River and its tributaries in Plymouth County. 

The origins of Mill Creek are still being debated. Some argue that these beginnings lie within the Great Oasis culture, while other researchers favor a more generalized Late Woodland origin. While most Mill Creek sites are small, occupying 1 acre or less, several are marked by extensive midden deposits which sometimes accumulate to depths of six feet (2 m) or more. These middens, which can be correctly described as trash heaps, are laden with prolific amounts of broken pottery, animal bone, charcoal, and lithic material. Three of the Mill Creek sites are known to be fortified and show evidence of a large ditch encircling each site. 

The Mill Creek inhabitants practiced a mixed economy, relying upon both horticulture and hunting as food sources. Maize was one of the most important foods grown, with chenopods (goosefoot), marshelder, and squash also being utilized. Large hoes manufactured from the scapula of bison were used to till the ground. The Mill Creek sometimes utilized a garden area composed of numerous mounds of earth, referred to by archaeologists as ridged fields. Bison, deer, and elk supplied the bulk of the meat resources, with water fowl, catfish, beavers, and squirrels also being hunted. 

One intriguing aspect of the Mill Creek culture is their long-distance connection with people leading a lifestyle completely different from themselves. The Mill Creek had established trade relations with the Middle Mississippian culture of the eastern woodlands, specifically those living in western Illinois. These relations are seen by the occurrence of locally made copies of Middle Mississippian ceramic vessels found at several Mill Creek sites and by Mill Creek vessels found at the Eveland site, a Middle Mississippian village located in the central Illinois River valley. Bison scapula hoes, bird-wing fans, and bone bracelets, all of which are Plains-derived traits, also occur in Middle Mississippian sites in the central Illinois valley, while Middle Mississippian Long-Nosed God masks are found at several Mill Creek sites. Other possible items traded between the two cultures include marine shell beads, bison robes, bird feathers, and hawk and eagle medicine bags. 

Whatever happened to the Mill Creek Indians of northwest Iowa? While no one knows for sure, most likely they moved up the Missouri River into South Dakota where they are known archaeologically as the Over Focus. Many researchers now believe that the Mandan and Hidatsa eventually developed from these Mill Creek roots. 

But why the reason for this movement? Climate changes, depletion of natural resources, or the arrival of the Oneota into northwest Iowa have been suggested as possible causal factors for this relocation. One current hypothesis is that the Oneota, by moving into areas of central and eastern Iowa, severed the trade routes between the Mill Creek and the Middle Mississippians of Illinois. Feeling isolated and encroached upon by the Oneota, the Mill Creek simply left northwest Iowa and headed west, away from the Oneota. 

Recent excavations at Mill Creek sites have been conducted at the Double Ditch site in O'Brien County and the Phipps site in Cherokee County. To learn more about the Mill Creek, see Exploring Iowa's Past by Lynn Marie Alex, Mill Creek Ceramics: The Complex from the Brewster Site by Duane C. Anderson, or Chan-Ya-Ta: A Mill Creek Village by Joseph A. Tiffany.