Nearly 1,000 years ago along the Mississippi River near present-day St. Louis, Cahokia became America’s first city. With 200 earthen pyramids, three distinct but connected precincts, and hundreds of rural settlements throughout the American Bottom floodplain and surrounding uplands, Cahokia was a phenomenon. At its peak, the core urban population is estimated to be about 20,000 people concentrated in a 6 square mile area, with a regional population greater than 50,000 people. Why did so many people come together to create Cahokia, and how did they do it? How did they support a large urban population, adapt to a loss of ecosystem services, and design a sustainable urbanism that was resilient to change? ISAS archaeologists are investigating these and other topics related to how Cahokians and other Mississippian people managed issues related to urbanism that we still face today.

  • Ancient Urbanism: How many forms of urbanism were there in the past, and how many are there today? While excavating an Indigenous neighborhood within Greater Cahokia’s East St. Louis precinct to make way for a new bridge across the Mississippi River, ISAS found that public and religious buildings were interspersed with homes as part of the urban planning of that section of the city. A century later, the neighborhood seems to have been dismantled, causing archaeologists to ask questions about the basis of city life.
  • Resource Management and Exploitation: Recent studies of deeply buried sediments from the middle of Cahokia do not support the idea that Cahokians mismanaged their environment. Quite the opposite. Cahokians were able to generate an urban environment without significant negative impacts to waterways and farmlands.
  • Climate Change: The latest paleohydroclimatological models show a correlation between the warmer, wetter climate of the early Medieval era (AD 900s–1000s), the adoption of corn, and Cahokian urbanization. The decline of the city might also correspond to droughts. Understanding the nuances of how climate did or did not cause cultural change and how people did or did not impact local ecology in the past has a direct bearing on our present struggles to plot our own future.
  • Corn and Cuisine: Corn formed a major component of Mississippian diets, but it is nutritionally deficient unless it is soaked in an alkaline solution, a process referred to as nixtamalization. The beginning of maize agriculture in the American Bottom coincides with the appearance of new pottery forms and heavy use of limestone that is suggestive of the creation of new culinary traditions, including using limestone to process, and possibly flavor, corn-based recipes.
man using EMI on plotted areas of earth

Dr. Jacob Skousen, ISAS research archaeologist, uses a non-invasive technique called electromagnetic induction (EMI) to detect the architecture of Mound 37 at Cahokia Mounds State Historic Site in Collinsville, Illinois. Monks Mound, the largest Indigenous earthwork in the Americas and largest pyramid north of Mesoamerica, towers in the background.

archaeologist excavating in Cahokia mounds

Dr. Caitlin Rankin, ISAS Geoarchaeologist, digs in the Cahokia Mounds.

aerial view of Cahokia Mounds excavation next to interstate

Aerial view of the Cahokia Mounds excavation.