Aerial view of huge mound at Cahokia, surrounded by flat land with grass and trees, Mississippi river in distance

Monk's Mound from above

Letter to Students

Dear Friends, 

I’m excited to share with you the story of Cahokia, the first city in America. My name is AJ and I’ve been an archaeologist for about 10 years. When I was in school I loved history and social studies, but I didn’t want to just read about history, I wanted to experience it by travelling. As an archaeologist, I’ve been able to travel to Egypt, Jordan, and Vietnam, working on excavations to find artifacts and other clues that tell us about life in the past. But my favorite project that I’ve worked on isn’t far away – in fact it’s right here in America at a place called Cahokia. 

Cahokia is an archaeological site in Illinois that was built and occupied by Native Americans from about 1000-1400 CE. I used to think that you had to go far away to find ancient ruins like pyramids, but Cahokia has tons of them with over 100 remaining today. Unlike the stone pyramids of Egypt, the pyramids at Cahokia are made of clay piled high into large mounds. The biggest mound at Cahokia, Monks Mound, is over 100 feet tall, 775 feet wide, and 950 feet long, making its base about the same size as the Great Pyramid of Giza. After climbing 154 steps to the top of Monks Mound, the view is amazing – it was basically America’s first skyscraper! 

I’ve included here information on astronomy, religion and sacrifice, and daily life at Cahokia. I also discuss why I think climate change is part of the reason why people eventually left Cahokia. It’s an important reminder of how climate change affected people in the past and how we can learn from that to help us fight climate change today. 

I hope you enjoy learning about this amazing place!


AJ White

Key Terms

Mound: Structure made of soil, gravel, sand, or other similar materials.

Great Pyramid of Giza: An ancient Egyptian tomb for the pharoah Khufu. It was originally 481 feet (146.5 meters) tall.

person crouched down in hole, looking up at camera, wearing hat and glasses

AJ White at an archaeological site



1000 CE Cahokia established as a large village with multiple mounds; people continue to arrive to the site
1100 CE Cahokia reaches its population maximum of approximately 15,000 residents
1150 CE A large Mississippi River flood hits the Cahokia region
1150 CE The first of several palisades is constructed around the center of Cahokia
1150 CE Cahokia’s population is in decline
1150-1200 CE A series of droughts strike the Cahokia area
1400 CE Cahokia is abandoned
1600 CE A much smaller group of Native Americans occupy the Cahokia area

Introduction to Cahokia

Cahokia is in the Mississippi River Valley near the confluence, a place where rivers come together, of the Missouri, Illinois, and Mississippi Rivers. It has been a special place for centuries. Today, it is home to St. Louis, one of the largest cities in the Midwestern United States. One thousand years ago, it was home to Cahokia, a Native American metropolis. Cahokia reached its highest population around 1100 CE with about 15,000-20,000 people, which was probably a little more than the populations of London and Paris at that time. For comparison, it was not until the late 1700s that American cities like New York City and Philadelphia had more people than Cahokia. While there were huge prehistoric populations all throughout North and South America, you can think of Cahokia as the first city in (what eventually became) the USA.

flyover of monks-mound, grass and trees, with large rectangular hill and smaller round hills

Aerial views of Monk's Mound and Twin Mounds

People have lived in the Cahokia region for thousands of years, but around 1000 CE local people and immigrants from other parts of the continent/other parts of the Mississippi River Valley began to gather there in large numbers. Archeologists call their way of life the ‘Mississippian culture’ and Cahokia was the largest and most important Mississippian site ever built. We do not know why people chose to come to Cahokia, but it is located at an important confluence of the Mississippi River where the valley is wide and can hold a lot of people and farms. As Cahokia grew more powerful, more immigrants arrived, perhaps against their will as captives from war or by choice as families looking for work and a good life. 

There are two main ideas for how politics at Cahokia worked: a single, powerful leader, like a president or shared power between multiple leaders, like senators. Evidence for a single, strong leader includes one mound much bigger than the others, Monks Mound, that may have housed the most important family at Cahokia, and human sacrifice at Mound 72 (see ‘Religion, Power and Sacrifice’ section for more information). On the other hand, the fact that there are many large mounds at Cahokia, not just Monks Mound, suggests that power may have been shared. Most likely, there was one leader or group that was more important than others, but their power was not total.

Cahokians farmed an early version of maize (another word for corn) that was smaller than the corn you see in stores today. They also grew squash, sunflower and other domesticated crops and also ate a variety of wild plants. They fished in lakes and streams and hunted birds, deer, and occasionally animals like beavers and turtles. Isotopes in bone from burials (see ‘Religion, Power and Sacrifice’ section for more information) tells us that more powerful people at Cahokia ate more meat and probably had a healthier diet than commoners. Although many people were involved in getting or making food in some way, there still were many other jobs at Cahokia: you could be a potter, flintknapper, beadmaker, builder, healer, priest, leader, or some combination of all these. People had free time too, and for fun would play games like chunkey. To play chunkey, you roll a stone across a field and then try to throw a spear as close to the stone as possible before it stops rolling, sort of like a more exciting and dangerous game of bocce ball. 

By 1150 CE, people started to leave Cahokia. Around this time a large wooden wall was built around the middle of the site, called a palisade, that archaeologists think meant the city was in trouble. By 1400 CE the area was abandoned. There are two main ideas for why people left Cahokia: societal problems and environmental problems. Societal problems could have been warfare, economic loss, or failures of government. Environmental problems could have been drought, floods, or environmental degradation, when people abuse their environment. It is most likely that Cahokia faced societal and environmental problems at the same time (just like the US is doing now!). It is important to note that the Cahokia area was home to a later Native American village and multiple Native American groups visit and use the site today; its abandonment was not the end of Native Americans at Cahokia.

Key Terms

Confluence: a place where two rivers join to become one larger river

Mississippian: the general way of life of people in the Mississippi River Valley from the Great Lakes to Louisiana from about 1000-1400 CE

Maize: corn, but with a smaller cob than what you see in stores today

Isotopes: atoms of the same element that have different weights and are present in different amounts in foods

Flintknapper: someone who makes stone tools like arrowheads

Chunkey: a ball game played in many Native American cultures, including at Cahokia in the past and by many tribes today

Palisade: a wall made out of posts stuck into the ground

Environmental Degradation: harming an environment through things like deforestation or pollution

Changing Narratives: Who Built Cahokia?

When European settlers and explorers first encountered ancient mounds in America, like the ones at Cahokia, many did not believe that Native Americans could have built them. These racist views led some to bizarre explanations, including giants, Vikings, or Atlanteans. Although many people did not believe these farfetched ideas, they fed into a common belief in the 1800s that Native American people were inferior and undeserving of their land. Some early archaeologists even tried to prove that Native Americans were recent arrivals and that an older, mysterious people built the mounds because artifacts found at the bottom of mounds were different from the tools Native Americans used in the 1700s and 1800s. Although a more accurate explanation is that Native Americans simply changed the type of tools they used, this idea helped justify the forced removal of Native Americans from their homes throughout the 1800s.

By the 1900s it was clear to archaeologists that Native Americans built and lived in Cahokia (this was clear to Native Americans the whole time, if only people would listen). Today many archaeologists focus on the abandonment of Cahokia and wonder what caused people to leave such a large and important city. The abandonment of Cahokia is a very interesting subject and many news stories and books have been written about the topic. Sometimes these stories romanticize Cahokia, calling it a ‘lost’ or ‘vanished’ city, and focus entirely on its ‘disappearance.’ This makes it seem that the Native American people who lived in Cahokia vanished as well, but that is not the case. Just as people today move to new places when their hometown isn’t working out for them, many people who lived at Cahokia moved to other parts of the Mississippian territory to join or start new settlements.

Animation showing sediment core, chemical structure of fecal biomarkers, and Horseshoe Lake

Sediment cores from Horseshoe Lake contain fecal biomarkers

Although there is little archaeological evidence for people at Cahokia past its abandonment at 1400 CE, scientists used fecal biomarkers found in a lake outside of Cahokia to prove that Native American groups used the area in smaller numbers from 1500 to at least 1700 CE, showing that Native American presence in the area did not end at the abandonment of Cahokia.

With all the emphasis on Native American decline, a later occupation of the area was missed. It is important to remember that although Native Americans faced many challenges in the past, including disease and violence, they did not disappear; in fact, there are several million people in the United States who identify as Native American today.

Key Terms

Romanticize: describe something in an unrealistic way to make it sound more interesting

Fecal Biomarkers: molecules from human poop that can be used to show that people were present at an area in the past

Climate Change at Cahokia

Climate change is a big problem today, but did you know that it was a challenge for people in the past as well? At Cahokia, the city grew and reached its height during the Medieval Climate Optimum (MCO), a period when weather in much of the world was stable and warm from about 900-1200 CE. Near the end of the MCO the climate around Cahokia started to change: a huge Mississippi River flood happened around 1150 CE and long droughts hit the area from 1150-1250 CE. Some scientists believe the flood and droughts were part of climate change as the MCO transitioned to the Little Ice Age (LIA; 1300-1800 CE), a period when much of the world had cooler weather. These climate changes were not caused by human activity, but they still affected human societies.   

We are not entirely sure how climate change affected Cahokia, but we do know that at the time of the flood and droughts in the late 1100s, the population of Cahokia began to decline as people moved away. Flooding of the Mississippi River today affects many people and causes billions of dollars in damage; it is likely that the flood around 1150 CE destroyed farms and possibly houses in the low-lying areas of Cahokia. Droughts would have made it difficult to grow crops, especially in the hills around Cahokia that did not retain water as well as other areas.

tops of buildings and trees visible above extensive floodwaters

Climate change did not destroy Cahokia, in fact people stayed at the site for another 200 years. However, it seems that climate change, in the shape of flooding and droughts, hurt some people more than others – people with farms in low-lying areas and in bad soil could make less food than their neighbors, which may have affected their decision to leave and try for a better life somewhere else. The story of Cahokia reminds us that climate change can create inequality, as is happening in the world today. 

Key Terms

Medieval Climate Optimum: a period when weather in much of the world was stable and warm from about 900-1200 CE

Little Ice Age: a period when much of the world had cooler, more unpredictable weather from about 1300-1800 CE

Astronomy at Cahokia

You might have heard of Stonehenge in England, but have you heard of Woodhenge? Woodhenge is the name of a series of large circles made of wooden posts at Cahokia. Woodhenge was originally 240 feet across with 24 wooden posts evenly spaced around it, like numbers on a clock. It was rebuilt several times to eventually be over 400 feet across with 72 posts. The posts were about 20 feet high, made from a special wood called red cedar. We theorize that they were probably painted red due to traces of ochre found by archaeologists in the ground at Woodhenge. Certain posts at Woodhenge align with the summer solstice, when the sun appears furthest north, the winter solstice, when the sun appears furthest south, and the spring and fall equinox, when the sun is exactly in the middle.

Animation, shadows from posts at Woodhenge shift from angled to straight as we move from winter solstice to spring equinox to summer solstice to fall equinox

While it is hard to prove what Woodhenge was used for, it was likely a sort of calendar that marked the changing of the seasons and the passing of time. The equinoxes and solstices were probably important dates when festivals and religious events were held and Woodhenge marked the occasions. It may have been used to view the moon and stars, so you can think of it as an ancient observatory. It may have also helped align the carefully built mounds at Cahokia, like how surveyors use special equipment in construction today. In any case, Woodhenge proves that people at Cahokia had a strong understanding of how the sun moves across the sky, what we know today as astronomy.

Key Terms

Woodhenge: a series of large circles made of wooden posts at Cahokia that align with astronomical features

Ochre: a red pigment made from the same mineral as rust

Solstice: when the sun is at its highest (summer) or lowest (winter) point in the sky and day or night is the longest

Equinox: when the sun is exactly between its highest and lowest points in the sky and day and night are about the same length

Religion, Power, and Sacrifice

Cahokia had over 100 large mounds spread across the land like skyscrapers in a city today. One of these mounds, Mound 72, contains the remains of 272 people buried in 25 separate places within the mound. In one burial, a man who archaeologists call ‘Birdman’ was carefully placed on a bed made from thousands of shell beads in the shape of a bird. He was surrounded by special items like jewelry, copper, and hundreds of arrowheads that had never been used. Archaeologists think these special items, called grave goods, have to do with religion. They were likely buried with this person to help him in the afterlife. Grave goods also tell us about a person’s importance. Birdman was probably really important and powerful because he was buried with so many nice things, similar to King Tut’s tomb in Egypt. 

Several men and women were buried next to Birdman and his special grave goods, which may mean that these people were his family members or important members of society. Other burials at Mound 72 include four young men without hands or heads and over 50 young women stacked together in rows. Archaeologists studied the amount of nitrogen isotopes in the bones from Mound 72 to learn what people ate. The most common type, or isotope, of nitrogen is nitrogen-14; the less common type, nitrogen-15 has one more neutron and so it is a little heavier. The bones of people next to Birdman have more nitrogen-15 than those of the young men and women buried farther away, meaning that they ate more meat and had a healthier diet. The young men and women probably had less power and did not enjoy a wide variety of foods.

animation, one skeleton on top of cloak, grave goods to the left, other burials to the right

Because the people next to the special grave goods and the young men and women a little farther away were buried at the same time as Birdman, many archaeologists think that they were human sacrifices who were killed to honor him or his family, show his power, or as an important religious act. The young men and women probably were forced to die and were chosen because they were not powerful people. However, the people next to Birdman may have chosen to die with him. A French colonist in 1725 witnessed the burial of a leader, named Tattooed Serpent, of the Natchez people in Mississippi. The Natchez had a similar way of life to people at Cahokia. At Tattooed Serpent’s funeral several commoners were killed, but some of his family and friends chose to join him in death. While we will never know for sure, it is possible that a similar event happened at Cahokia. Although Mound 72 tells a dramatic story, it is the only example of human sacrifice archaeologists have found at Cahokia and the practice was rare, possibly happening only once. 

Mound 72 shows us the importance of religion and power at Cahokia. People were buried in special ways because of their religious beliefs and some people were more powerful than others, having fancier grave goods and the power of life and death over commoners. Human sacrifice has happened throughout time all over the world. Cahokia shows us that human sacrifice is complicated – at Mound 72 some people were certainly forced to die, but others may have chosen to die along with someone they loved or found very important.

Key Terms

Grave Goods: the items placed in a burial after someone dies

Nitrogen Isotopes: types of nitrogen atoms that exist in nature and are present in different amounts in foods

Natchez People: a Native American tribe with a way of life similar to Mississippian culture

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Ancient Civilizations of the Americas by Anna Guengerich 2.12.2015