Cahokia’s Collapse: Climate Hypothesis

By: Hudson Double

Fig 1: Cahokian Mounds Photographed by Ko Hon Chiu Vincent

Nearly 1000 years ago a new city was founded and would eventually grow to a size of between 10-20,000 people over the coming years (Pauketat 2009). This great city, known as Cahokia, was not in Europe, but sat on the banks of the Mississippi, just a few miles away from what has since become St. Louis. Around the year 1050 CE, the city quickly expanded, growing into the largest city ever in North America up to that point in time, but just a few hundred years later, from 1250-1350 CE, the city would quickly unravel (Pauketat 2009: 138). Though there are multiple theories behind the collapse of Cahokia, through this post I intend to examine the idea of climate change acting as the catalyst for the collapse of the city.

Fig 2: Settlements Around Cahokia

To begin, this theory which has been discussed in the media repeatedly over the past few years essentially states that Cahokia both formed and collapsed as a result of environmental factors. Starting with the methodological approach, the primary way by which climate records on the region were gathered was by collecting samples of mud from the bed of lake Martin. By examining the calcium carbonate crystals between the stratigraphic layers, they were able to create an accurate record of rainfall over specific periods of time. These records showed that there was increased rainfall starting about 100 years before the foundation of the city in 900 CE (Chen 2017). Increased temperatures and rainfall as a result of the Medieval Climatic Anomaly—also known as the Medieval Warm Period—resulted in increased fertility, allowing for corn to thrive. As a result, isotopes found in corn began being found in the Skeletons of Mississippian skeletons within decades, and continued through until the foundation of the city (Chen 2017).

Fig 3: The Famous Monks Mound and Central Plaza

Following the foundation of the city, the climate remained fairly active and fertile for the following centuries, before rapidly cooling around the year 1200 CE (Chen 2017). Furthermore, starting around the year 1150 CE there had been a series of droughts which had seriously impacted the farming potential of Cahokia, and continued through the following centuries as the climate cooled (Benson 2009: 467). Evidence coming from analyzing fecal particles in Horseshoe lake, just north of Cahokia, lends further evidence for the idea the city may have been struggling to effectively produce food, leading to an exodus of people before 1350 CE (White 2019). Overall, though there is no way to know for sure what caused the collapse of Cahokian civilization, there is considerable evidence lending credence to the idea of climate factors ushering in the end of the civilization. While there are several other environmental theories, mainly surrounding overharvesting of resources, the evidence provided by the analysis of particles in nearby lakes and more provides profound insight into the events that took place in the great city of Cahokia.


  • University of Wisconsin-Madison. (2019, February 25). Climate change contributed to fall of Cahokia. ScienceDaily. Retrieved November 23, 2023 from link
  • Vincent, Ko Hon Chiu. “Cahokia Mounds State Historic Site.” Cahokia Gallery – UNESCO World Heritage Centre, UNESCO World Heritage Centre, Gallery. Accessed 24 Nov. 2023. 
  • “Monumental Grandeur of the Mississippi Valley”: The Mounds of Native North America – Scientific Figure on ResearchGate. Available from: Link [accessed 24 Nov, 2023]
  • Benson, L. V., Pauketat, T. R., & Cook, E. R. (2009). Cahokia’s Boom and Bust in the Context of Climate Change. American Antiquity74(3), 467-483.
  • Everding, Gerry. “Women Shaped Cuisine, Culture of Ancient Cahokia – the Source – Washington University in St. Louis.” The Source, Washington University St.Louis, 13 Nov. 2020, Source
  • Shukla, Priya. “Human Poop Reveals That Climate Change Caused the Fall of Cahokia, a Medieval Native American City.” Forbes, Forbes Magazine, 12 Apr. 2019, Forbes
  • White, A.J., and Lora R Stevens. “Fecal Stanols Show Simultaneous Flooding and Seasonal Precipitation Change Correlate with Cahokia’s Population Decline.” PNAS, Northwestern University, Feb. 2019, link
  • Chen, Angus. “1,000 Years Ago, Corn Made This Society Big. Then, a Changing Climate Destroyed It.” NPR, NPR, 10 Feb. 2017, NPR

Image References

  • Fig 1: Vincent, Ko Hon Chiu. “Cahokia Mounds State Historic Site.” Cahokia Gallery – UNESCO World Heritage Centre, UNESCO World Heritage Centre, Accessed 24 Nov. 2023.
  • Fig 2: Benson, L. V., Pauketat, T. R., & Cook, E. R. (2009). Cahokia’s Boom and Bust in the Context of Climate Change. American Antiquity, 74(3), 467-483.
  • Fig 3: “Monumental Grandeur of the Mississippi Valley”: The Mounds of Native North America – Scientific Figure on ResearchGate. Available from: [accessed 24 Nov, 2023]

Further Reading

Clovis-First Theory: The Sites That Disprove it

The Clovis-First theory of human migration, a once widely accepted theory of human migration to the Americas, states that human inhabitation of the continent began between 12,900 and 13,100 years ago (Lovgren, 2021). A basic overview of the Clovis-First theory is that the Clovis people—named for Clovis, New Mexico, where lithics were uncovered in 1934—were the first to migrate to the Americas, coming over an ice bridge in Beringia during the later stages of the last glacial maximum. Over time, these mammoth hunters would disperse across the continent with their distinctive lithics being discovered at several archeological sites.

Fig 1: Map of Clovis Sites Across north America

Though there is evidence to support the idea that Clovis people migrated from Asia (Gilbert, 2008), there is little evidence to prove that they were the first. Furthermore, over recent years the discovery of further sites around the country lends credence to the theory that many different groups of humans migrated to the Americas over several periods of time. Though there are many to choose from, I am going to examine only two different archeological sites, both of which predate the Clovis people.

Fig 2: University of Oregon Archeology Field School excavation of Rimrock Draw where 18,000+ year old artifacts were found.

The first site to catch my attention while I was researching dates back 18,000 years, in what is now Oregon. Back in 2012, archeologists uncovered teeth belonging to a—since extinct—species of camel, which had been buried by the eruption of Mount St. Helens over 15,000 years ago (Pettigrew, 2023). As the researchers dug deeper, they also discovered a blade which had bison blood residue on it; due to stratigraphic position, it is thought to be even older than the camel’s teeth. Upon carbon dating the teeth, researchers discovered that the teeth themselves dated back to over 18,200 years ago, confirming that this site pre-dates the Clovis peoples by over 4,500 years at the low end.

Fig 3: Map Showing Coopers Ferry Archaeological Site

The second important site that caught my attention was Coopers Ferry, a site in Idaho dating back over 16,000 years. At Coopers Ferry, over 200 artifacts were found, including stone tools, lithics, and bone fragments (Davis, 2019). Based on the fact that an opening in the ice caps across Canada would not appear for up to another millennium, it is likely that the people of Coopers Ferry arrived from the Pacific (Wade, 2019). Further credence is given to this theory based on the position of the site along a river, where humans likely came upstream from the ocean. Due to those facts, Coopers Ferry and Rimrock Draw fundamentally contradict the Clovis-First theory, and redefine the dynamics of human dispersal across the Americas.


Erlandson, J. M. (2013). After Clovis-first collapsed: Reimagining the peopling of the Americas. Paleoamerican odyssey, 127-131.

Lizzie Wade, Ancient site in Idaho implies first Americans came by sea. Science 365,848-849(2019). DOI:10.1126/science.365.6456.848

Fiedel, S. J. (2014). Did pre-Clovis people inhabit the Paisley Caves (and why does it matter)?. Human Biology, 86(1), 69-74.

Goebel, T., Waters, M. R., & O’Rourke, D. H. (2008). The late Pleistocene dispersal of modern humans in the Americas. science, 319(5869), 1497-1502.

Gilbert, M. T. P., Jenkins, D. L., Gotherstrom, A., Naveran, N., Sanchez, J. J., Hofreiter, M., … & Willerslev, E. (2008). DNA from pre-Clovis human coprolites in Oregon, North America. Science, 320(5877), 786-789.

Hutcherson, E. (2023, July 15). Archaeologists find new evidence in southern Oregon that suggests human habitation 18,000 years ago. OBP.

Stastna, K. (2012, July 13). Clovis people not 1st to arrive in North America | CBC News. CBCnews. CBC.

Pettigrew, J. (2023, July 11). Possible proof of oldest human-occupied site found in Oregon, dating back over 18K Years.

Lovgren, S. (2021, May 3). Clovis people not First Americans, study shows. Science. Article

Waters, M. R., Stafford Jr, T. W., & Carlson, D. L. (2020). The age of Clovis—13,050 to 12,750 cal yr BP. Science Advances, 6(43), eaaz0455.

Davis, L. G., Madsen, D. B., Becerra-Valdivia, L., Higham, T., Sisson, D. A., Skinner, S. M., … & Buvit, I. (2019). Late upper paleolithic occupation at Cooper’s Ferry, Idaho, USA,~ 16,000 years ago. Science, 365(6456), 891-897.

Fig 1: Waters, 2020

Fig 2: Hutcherson, 2023

Fig 3: Davis, 2019

Further Reading