10/15/2026
60 years ago this week, the National Historic Preservation Act passed into law! Section 106 of the NHPA dominates the archaeological profession in the US, and it is critical to archaeological research. Section 106 compliance work, notably Phase III excavations, have contributed significantly to advancements in Iowa archaeology and to our collective knowledge of the past—including what we know about corn!
The oldest evidence of corn agriculture in Iowa comes from the Rainbow site in Plymouth County. This site was found in 1977 during an archaeological reconnaissance survey of the proposed location for a (water impounding) soil erosion structure in the Held Creek watershed. It’s reported that a single maize seed was found in a Late Middle Woodland level during the salvage excavations. Corn’s scant presence in Late Woodland sites across Iowa indicates that it was a minor contribution to the diet at that time. But starting 1000 years ago, corn agriculture intensified and became a dietary staple! Archaeologists confirmed this in 1998 during a Section 106 data recovery excavation in Woodbury County. The Cowan site, a rare Great Oasis culture farming hamlet, was mitigated prior to the construction of the US 75 bypass around Sioux City.
The photos featured here are from OSA’s excavations at the Cowan site.
