Cahokia Mounds of Illinois: An Unparalleled Native American City

In Southern Illinois, the Cahokia Mounds are an unsung archaeological treasure. Along the Mississippi River in Collinsville, across from St. Louis, the largest pre-Columbian Native American settlement north of Mexico flourished from around 800-1200 CE. Nicknamed, “America’s Forgotten City” or “City of the Sun,” the site once covered nearly 4,000 acres and served up to 40 thousand people. Additionally, the region served as an economic distribution center and hub of culture and religion. During its height, this unparalleled city housed 120 mounds. Today, the Cahokia Mounds State Historic Site is home to about 80 mounds that served various purposes.

Artist rendering of Cahokia AD 1150-1200.

Artist’s (William Iseminger) depiction of Cahokia, circa 1150-1200 CE. Photo by Historic Mysteries at Cahokia State Historic Site.

Mississippian Culture

Cahokia was both the origin and the pinnacle of the Mississippian culture. Also previously known as the “mound builders,” the Mississippians lived in the Mississippi Valley, Ohio, Oklahoma, and into the midwest and southeast. They worshipped the Sun and other celestial beings within a well-developed religion. Additionally, the culture revolved around warfare, and human sacrifices were common. Agriculture was important to their survival, and they grew three crucial crops known as the three sisters: corn, squash, and beans. Mississippians also constructed mounds and earthen pyramids of all sizes.

Mysterious Clava Cairns of Scotland

A chiefdom or complex chiefdom carried out the governance of the Mississippian society. Through this system, one or just a few individuals held all the political and religious power. Their settlements innovated a hierarchal city design, whereby the major center consisted of a large number of earthen structures. This geopolitical nucleus had complete control over the lesser regions that contained fewer to no structures.

Facts About the Cahokia Mounds

  • What types of mounds were there? Flat-top platform, conical, and ridge-top. The most common was the platform mound.
  • When were the mounds built? As the Mississippian culture grew in the region from around the 9th century to the 13th century.
  • What was the purpose of the Cahokia Mounds? Platform mounds with flat tops supported structures, such as temples or dwellings, and stages for festivals and religious/political ceremonies. Conical and ridgetop mounds may have served as burial sites and landmarks.
  • Who discovered Cahokia? French explorers came upon the settlement in the 1600s and named the site after the tribe living there at the time.
  • What materials were used for the mounds? Clay, topsoil, shells, or stones. The largest mounds contained a high percentage of clay to hinder water seepage and erosion.
  • How were the Mississippian mounds constructed? Workers dug or gathered building material from one area and carried it in baskets on their backs to the construction site. They tamped soil and clay one layer at a time to create the earthen mounds.

Illustration of Mississippian mound construction.

Diagram showing the various components of platform mounds constructed by Native Americans in the eastern United States. CC3.0 Herb Roe.

Rise of Cahokia

Small villages situated along Cahokia Creek were the first to dot the area beginning around 600 CE. The climate began warming and more rain fell in the region. Hence, agriculture intensified and villagers could now grow an abundance of corn and other crops. As a result, thousands of individuals migrated to the area.

Blythe Intaglios Geoglyphs in California’s Desert

By about 1000 CE, the Mississippians had built one of the greatest Native American civilizations. Some people have referred to it as a kingdom; from Cahokia, many Mississippian settlements sprung up from the Midwest as far as the Great Lakes across the entire Southeastern region of North America, including the Gulf Coast. The city became the pre-eminent center of religious and political power and may have even controlled a vast network of trade and economies across the Mississippian reach.

The Cahokian settlement appears to be the birthplace of many Native American Indian customs, practices, and beliefs. In fact, according to Timothy Pauketat who wrote Ancient Cahokia and the Mississippians, Cahokians created the early Mississippian culture altogether. They had sophisticated farming tools, pottery, astronomy, and copper-work. Religion, cosmology, and a pantheon of gods were central in the Mississippian life and led to the development of many temples. It was a culture that spread so far and wide that experts named the collective cultural commonalities of the region (religion, cosmology, art, iconography, etc.) the Southeastern Cultural Complex, or the S.E.C.C.

Game of Chunkey

Another prominent cultural identifier originated at the Middle Mississippian site. The game of chunkey emerged during the region’s early occupation. This was an important sport in which a player rolled a stone disc and had to throw a spear to land as close to the stopped stone as possible. “Chunkey was played in huge arenas as large as 47 acres (19 ha) that housed great audiences designed to bring people of the region together (i.e. Cahokians, farmers, immigrants, and even visitors” (Pauketat 2006). The stakes were high in this game. Indeed, family members and players became sacrifices in the case of a loss.

Monks Mound

Of the many structures in the City of the Sun, the most impressive is Monks Mound pyramid. The enormous construction was built up in as many as fourteen successive stages between the years 900 and 1100 (Unesco). Containing over 25 million cubic feet of soil, the mound rises 100 feet into the air and covers 14 acres. These staggering figures make the Monks Mound pyramid the largest prehistoric earthen structure north of Mexico.

Monks mound and daily life at Cahokia Mounds State Park

Artist’s (Michael Hampshire) interpretation of Monks Mound towering over daily life. Photo by Historic Mysteries at Cahokia State Historic Site.

Planners positioned Monks Mound as the towering central structure amidst four large plazas in the city. A large wooden building surrounded by a palisade sat atop the mound. The purpose of the building is uncertain. However, because few artifacts related to dwellings existed during excavations, experts believe it may have been a place for the dead or a site of political and religious council. Religious ceremonies may have taken place there as well, as Monks Mound may have held a central place in the Mississippian cosmos that connected the “Sky Realm” with the “Earth Realm.” Thus, Mississippians would have regarded the site as a highly potent religious and political symbol. (Romain).

Monks Mound looking west.

View of Monks Mound today looking west. Erosion appears to have altered its original form. Photo: Historic Mysteries.


It was important for the Mississippians to know when to plant, harvest, and celebrate the solstices and equinoxes. Therefore, they had at least five woodhenges strewn around the city that served as calendars at various times. This allowed them to track the sun and seasons with a high degree of accuracy. Circular configurations of wooden posts served as the markers. Four equidistant posts marked the solstices and equinoxes, while posts in between tracked the mid seasons.

Woodhenges at Cahokia Mounds tracked the seasons.

Woodhenge construction and design of beaker (bottom R) with sun symbol found near a winter solstice pole. Artist L.K. Townsend. Photo: Historic Mysteries, Cahokia State Historic Site.

In 1961, Dr. Warren Wittry first discovered a set of 28 poles that stretched 410 feet in diameter. Four additional circles surfaced later. Of these five circular patterns built out of the red cedar (sacred to the Native Americans), one set contains 24 posts, one has 36, one has 48, one has 60, and the last circle which has yet to be fully excavated is made of 72 posts. Due to the discovery of red ochre near the posts, researchers believe they were originally painted red.

An Ancient Winter Solstice Temple in Ireland

Beyond serving as a calendar, the structures may have had another purpose. Experts have suggested that their design was also an engineering device that assisted city planners with the construction and layout of the city. Also, because of the red ochre found near the site, others have suggested that the Woodhenge circles had a religious significance.

Mound 72

The burial complex in Mound 72 is one of the most significant discoveries in Cahokia. Between 1967 and 1971 teams from the University of Wisconsin-Milwaukee excavated the ridgetop mound. Its length is about 140 feet, while the width and height are 72 feet and 10 feet, respectively. Within the mound, researchers found several smaller mounds that contained more than 250 skeletons. The Mississippians had covered those sub-mounds with soil and added another layer to give it its final outer shape.

The most important feature of Mound 72 is the central placement of a man and woman in a grave with a layer of more than 20,000 shell beads. The shells lay in the shape of a falcon or the “Birdman,” a powerful Sky Realm symbol and deity. Initially thought to be two males, forensic work by Emerson et al. 2016 determined that a female lay under the shell bead layer. The male lay on top of the female above the beads. Interestingly, this configuration may allude to themes of cosmogenesis and fertility. Additionally, other skeletons and highly valuable grave goods accompanied the couple in the grave.

Within other sub-mounds in Mound 72, researchers discovered numerous sacrificial victims and other individuals that suffered violent deaths. For example, one of the mounds contained 53 young females — all of them perished through sacrifice.

Experts also found that Mound 72 is aligned with Monks Mound along its horizontal axis and may have been a deliberate connection. Therefore, Cahokians may have held the belief that spirits traveled along the axis to and from the Upperworld or “Sky Realm” (Romain).

Collapse of Cahokia

Evidence suggests that the collapse of the region began during the 1200s. According to Pauketat, experts have not found any cemeteries dating later than 1275-1300 CE. Thus, it was around this time that the Mississippians began to abandon the area permanently.

Scholars have theorized a number of possible reasons for the collapse, such as food shortages, social pressure from competing tribes, and invasions that desecrated the religious sites. There is a strong possibility that climate change and the resultant natural disasters and social upheaval may have made the area unliveable.

Research on Devastating Events

1). Broxton Bird, a climatologist from Indiana University-Purdue University Indianapolis headed a study that he published in 2017. By taking ancient calcite samples in Matin Lake, Indiana, he and his team determined the precipitation levels throughout the years. Results of the study indicated that beginning around 1250 CE, climate change took over the midcontinental U.S. Around that time, a dry period begins. Also around this time, there is evidence of wars, social destabilization, and final abandonment at Cahokia. By 1350 CE, there was a serious drought brought on by dry arctic air. This was the start of the Little Ice Age, which lasted 500 years.

2). Floods often go hand-in-hand with dry spells when large rainfall occurs during droughts. In another study, Samuel Munoz and Jack Williams took core samples up to 2,000 years old from two lakes in the Mississippi floodplain. They saw that prior to 600 CE there were many floods. Then there was a period of no floods until 1200 CE. During the floodless period, Cahokia flourished. After the flood of 1200, the population declined until complete abandonment.

3). The changes in the climate and the flood event may have severely affected corn production. Thus, famine and hunger would have inevitably led to major upheavals in the large population. As a result, Mississippian society in the region began to collapse. Signs of the destruction of the palisades and of increased sacrifices and warfare increased after 1250 CE. By the end of the 14th century, residents had migrated south and east to areas with more stable climates.

Preservation of the Cahokia Mounds

The Historic Site in the state of Illinois protects more than 2,220 acres of the original 4,000 acres. This includes approximately 70 of the 80 remaining mounds. In 1964 the Federal Government designated the site as a Historical U.S. Landmark. Additionally, UNESCO named it a World Heritage Site in 1982. It is home to the Cahokia Mounds Museum Society that strives to preserve and understand the ancient culture and traditions of the Native Americans.

Due to its vast size and complex architecture, European settlers were amazed when they first encountered the mounds. They could not believe Native Americans could have built such a city. Therefore, they thought it was the work of another group, such as the Vikings or Israelites. Archaeology has taught us otherwise. We know they were skilled builders, because of the structures they left behind. They possessed the organization and leadership to develop a prosperous urban city. And the many artifacts of the region reveal immense artistry and creativity. Little by little, the true depth of their belief systems and way of life are slowly coming to light.

Additional references:
Emerson, T. E., Hedman, K. M., Hargrave, E. A., Cobb, D. E., & Thompson, A. R. (2016). Paradigms Lost: Reconfiguring Cahokia’s Mound 72 Beaded Burial. American Antiquity.
Pauketat, Timothy R. Ancient Cahokia and the Mississippians. Cambridge: Cambridge Univ. Press, 2006.
Romain, William F. “Monks Mound as an Axis Mundi for the Cahokian World.” – Share Research. Accessed February 12, 2019.

Share Your Thoughts

Kimberly Lin

Kimberly is a writer and the content manager for Historic Mysteries. If she's not plunging down the SEO rabbit hole, she's visiting some ancient site in Italy, where she currently lives in the middle of an active caldera. Kimberly will continue to venture around the world and write about the history she encounters.

Historic Mysteries