The Mystery of America’s Lost City

From studying artifacts left behind, historians believe small groups of Indigenous people started living in the southern Illinois area around 8000 b.c. Around  700 A.D., a larger settlement began to form, at the junction of the Missouri, Mississippi, and Illinois rivers. 

The settlement, which would become Cahokia, had fertile soil and plentiful rain, so settlers could grow bounties of corn and other crops. The settlers could also travel along the rivers to nearby villages to trade. 

Word of the growing city likely spread, attracting people from far and wide. About 20 percent of the residents came from other places, says Lori Belknap, who runs the Cahokia Mounds State Historic Site. Their varied languages and traditions blended, turning Cahokia into a melting pot of cultures—not unlike modern cities today. 

Historians studied artifacts left behind. They believe small groups of Indigenous people started living in the southern Illinois area around 8000 B.C. Around 700 A.D., a larger settlement began to form. It was at the junction of the Missouri, Mississippi, and Illinois rivers.

That settlement became Cahokia. It had rich soil and plenty of rain, which meant settlers could grow a lot of corn and other crops. Settlers could also travel along the rivers to nearby villages to trade.

Word of the growing city likely spread. That attracted people from far and wide. About 20 percent of the residents came from other places, says Lori Belknap. She runs the Cahokia Mounds State Historic Site. People’s varied languages and traditions blended. This turned Cahokia into a melting pot of cultures—like modern cities today.

If you look at an aerial view of Cahokia now, you can still see the remains of many of its mounds. These earthen hills were not the first of their kind. Indigenous people throughout the Americas started building mounds about 5,000 years ago. But Cahokia had a lot of them, about 120, and they were mostly bigger than earlier ones. 

Some mounds were used for burials of powerful leaders, some for ceremonial functions. People who probably had a special status in the city lived on the tops of others, says Belknap.

At the center was Monks Mound. It remains the largest structure of earth ever made in the Americas, built by hand with millions of baskets of soil. Historians believe tribal leaders likely ruled from a building at its top.

If you view Cahokia from overhead now, you can still see the remains of many of its mounds. These earthen hills were not the first of their kind. Indigenous people throughout the Americas started building mounds about 5,000 years ago. But Cahokia had a lot of them, about 120. And most were bigger than earlier ones.

Some mounds were used to bury powerful leaders. Some were used for ceremonies. People who probably had a special status in the city lived on the tops of others, says Belknap.

At the center of Cahokia was Monks Mound. It is still the largest structure of earth ever made in the Americas. It was built by hand using millions of baskets of soil. Historians believe tribal leaders likely ruled from a building at its top.

Why would anyone leave such a remarkable city?

There wasn’t a massive flood or a devastating tornado. In fact, there is no evidence of a single disaster that would have driven everyone away.

No one knows exactly why people left. But experts have theories. Some believe that the climate began to dry up, depleting the stores of corn. So people may have left to follow buffalo herds as a source of food. 

According to Belknap, residents may also have departed because of an unpopular leader or diseases spreading through the city. “It may have taken only a couple of changes for people to start leaving,” she says. 

What experts do know is that as people left, they took their way of life with them. Called Mississippian culture, it centered around growing corn and building mounds. So, even as Cahokia disappeared, its influence spread in all directions. 

Why would anyone leave such a great city?

There was no giant flood or destructive tornado. There is no evidence of a single disaster that would have driven everyone away.

No one knows exactly why people left. But experts have theories. Some believe that the climate began to be much drier, reducing the supply of corn. So people may have left to follow buffalo herds as a food source.

According to Belknap, residents may also have left because of an unpopular leader, or diseases spreading through the city. “It may have taken only a couple of changes for people to start leaving,” she says.

There’s one thing experts do know: As people left, they took their way of life with them. Called Mississippian culture, it was centered around growing corn and building mounds. So even though Cahokia disappeared, its influence spread in all directions.

Today Cahokia’s legacy lives on. Indigenous Americans including the Osage in Oklahoma and the Omaha in Nebraska trace their histories back to the great city. 

Over the centuries, many of Cahokia’s mounds have been flattened for roads and homes. About 80 remain. The largest is open to the public as part of the Cahokia Mounds historic site. You can climb up the 156 steps to the top of Monks Mound and imagine a vibrant world below.  

Some of the descendants of Cahokia are working to turn the site into a national park. Archaeologists still work there—looking for more answers to Cahokia’s mysteries.

Cahokia holds a spiritual connection for those who trace their roots to it, says Osage historian Andrea Hunter. “There are strong feelings because there’s so many of our ancestors that are buried there,” she told National Geographic. “Our community members can connect to that and feel that.” 

Today Cahokia’s legacy lives on. Indigenous Americans trace their histories back to the great city. That includes the Osage in Oklahoma and the Omaha in Nebraska.

Over the centuries, many of Cahokia’s mounds have been flattened for roads and homes. About 80 remain. The largest is open to the public as part of the Cahokia Mounds State Historic Site. You can climb up the 156 steps to the top of Monks Mound. You can imagine a vibrant world below.

Some of Cahokia’s descendants are working to turn the site into a national park. Archaeologists still work there. They are looking for more answers to Cahokia’s mysteries.

Cahokia holds a spiritual connection for those who trace their roots to it. That is according to Osage historian Andrea Hunter. “There are strong feelings because there’s so many of our ancestors that are buried there,” she told National Geographic. “Our community members can connect to that and feel that.”