How did people create Cahokia, an ancient American Indian metropolis near present-day St. Louis? And why did they abandon it? Archaeologists are piecing together the answers—but Cahokia’s story isn’t finished yet. Hear how an Osage anthropologist is protecting the remaining burial mounds and sacred shrines so the descendants of Cahokia’s founders can keep its legacy alive.
AMY BRIGGS (HOST): Tucked away in St. Louis, Missouri, in a southern section of the city just between the Mississippi River and Interstate 55, there’s a historic landmark. But you’d never know it. It’s on a road that’s easy to miss and frankly pretty beat-up. There’s not much along it—a billboard, a couple of generic industrial buildings. Driving down it can make someone, like our senior editor Eli Chen, wonder if they’re even in the right place.
(Voice of GPS navigation: “The destination is on your right. Sugarloaf Mound. Arrived.”)
ELI CHEN (SENIOR EDITOR): Wait, this is it?
BRIGGS: In front of her is a small, 40-foot hill. It has two tiers: a lower one with a one-story house on top and a higher one covered in weeds and bushes. A short flight of concrete stairs leads up the side of the taller one, but access is restricted by a chain-link fence around the property. A sign on a nearby telephone pole makes it clear. It says, No Trespassing, and it’s marked with the seal of the Osage Nation.
ANDREA HUNTER (OSAGE TRIBAL HISTORIC PRESERVATION OFFICER): The descendants of the people that lived there are still very much alive and well. We just happen to be over in Oklahoma.
BRIGGS: Andrea Hunter is a member of Osage Nation. She’s an archaeologist and directs the tribe’s historic preservation office. This hill is actually a mound built by American Indians. We don’t know exactly how old it is, but it could be more than a thousand years old. Later, in the 18th century, people who settled in St. Louis called it Sugarloaf Mound because they thought it had a similar shape to the hard loaves that sugar was transported in back then.
Centuries before, the ancestors of the Osage lived in the region that includes what is now St. Louis.
HUNTER: For the Midwestern United States, the archaeological record is difficult to find, for one because everything erodes—you know, our climate destroys that footprint. But at Sugarloaf Mound, you see something visible of the past.
BRIGGS: Sugarloaf Mound is just one of the sites built by the Osage ancestors. But they left an even bigger mark. Starting around the year 1050, they built a city that today is known as Cahokia. It was the largest American Indian city north of the Rio Grande before Europeans arrived. Cahokian culture spread up and down the Mississippi River, and they left hundreds of mounds dotting the landscape. But many of them have been completely destroyed in the last three centuries. Andrea wants to protect the ones that remain—and wants to remind people who built them.
HUNTER: The general public does not know all of the past, and so we're really trying to make that effort to inform the public of the rich history that is there.
BRIGGS: The mounds—as well as many other American Indian heritage sites—are in danger of disappearing, either from natural forces or human carelessness. Plus, they’re often scattered across private land, which can make it hard for Andrea to access them. But she needs to do everything she can to protect these places so that this history isn’t lost to the descendants of the people who built them.
I’m Amy Briggs, executive editor of National Geographic History magazine, and this is Overheard, a show where we eavesdrop on the wild conversations we have at Nat Geo and follow them to the edges of our big, weird, beautiful world.
This week: the fight to preserve Native American heritage sites. We’ll explore the wonders of Cahokia—its unprecedented rise, its eventual abandonment, and the cultural legacy left behind. We’ll also meet the people keeping that legacy alive today—how descendants of those mound builders are fighting to save what’s left, including Picture Cave, a shrine that the Osage consider to be their most sacred site.
More after the break.
Today many members of the Osage Nation live on a reservation in northern Oklahoma. But if you trace back Osage history—past the land grabs that pushed them off their ancestral home—the tribe has a much bigger footprint. Andrea Hunter says around 500 A.D., ancestors of the Osage were migrating across middle America, and they found a home along the Mississippi River.
HUNTER: Over the next couple of hundred years, our populations grew. You know, our knowledge of the resources and technology grew, and we started culminating in that St. Louis area.
BRIGGS: That culmination led to Cahokia. It’s located in what we know as southwest Illinois, just across the Mississippi River from St. Louis. Over the next few centuries, more American Indians would be living in Cahokia than in any other place in what’s now the United States. So what made this a special place?
(To Tim Pauketat) So let's dive right in. Let's talk about Cahokia. How did it start?
TIM PAUKETAT (ARCHAEOLOGIST): You know, of course, that's the $10,000 question. How did it start?
BRIGGS: This is Tim Pauketat. He’s an archaeologist at the University of Illinois Urbana-Champaign. He directs the Illinois State Archaeological Survey, and he’s also a National Geographic Explorer. Tim has 30 years of experience excavating American Indian sites near the Mississippi, including Cahokia. And he says you can point to some special qualities that make this an ideal place for a city.
For one, it’s where the Missouri River joins the Mississippi. That’s the same reason this spot later became an attractive location for French fur traders when they built the city of St. Louis. But there’s another reason that’s less obvious. The landscape all around Cahokia is full of caves.
PAUKETAT: And caves like this are—for many Native North American people, present and past—you know, portals into an underworld or into a world of ancestors. And so you have cave paintings, you know—you have shrines next to these access points into these caves, which are often just sinkholes. And that’s an attraction.
BRIGGS: Then around 900 A.D. a couple of things happened that made Cahokia even more attractive. Corn was grown in the area for the first time. And the climate became a little warmer, with more rain, so there was plenty of corn to go around, and that’s when Cahokia took off.
PAUKETAT: You go from before 1050, when you have kind of a big village occupying the site of Cahokia—probably 2,000 to 3,000 people. And then within a generation it goes—it's up to beyond 10,000 people.
BRIGGS: At its peak in the 12th century, as many as 20,000 people may have lived in Cahokia. So the name “Cahokia” came later. We actually don’t know what its people would’ve called the city or themselves. Researchers use the broad term “Mississippian culture” for this time period. Tim says there’s evidence people migrated from other areas, so it was probably a melting pot of cultures and languages. And it all came together really quickly.
PAUKETAT: But in happening fast, we know that it wasn't just a slow, evolutionary kind of development. It involved actual human beings, you know, making decisions—probably a good deal of politics and kind of coalition building to bring about a very—what was, especially for the Mississippi Valley, you know, a very new social order.
BRIGGS: Tim’s research has focused on the role religion played in that new social order. Religion would have been central to politics and the economy—basically every part of society. And you can see remnants of it at the Cahokia site today. American Indians started building mounds more than 5,000 years ago. But the Mississippians? They took mound-building to new heights.
Cahokia’s most dominant feature is known today as Monks Mound. It’s now a massive grassy mound. It’s a couple of wide rectangles stacked on top of each other, like a step pyramid. The mound is a hundred feet tall, with a footprint larger than the Great Pyramid of Giza. It’s made entirely of earth, and it’s bigger than any other human-made earthen structure in all of North America. Today you might see people jogging and families strolling there, but in its prime it looked very different.
PAUKETAT: And it would have had very sharp, 45-degree-angle sides—you know, faceted. Probably kept very clean, free of most weeds and grasses. Today it looks—you know, it's slumped a little. It's eroded. It's covered with European, you know, invasive grasses. So it looks a little different than it would’ve.
BRIGGS: So what would have happened at Monks Mound in Cahokia’s heyday?
PAUKETAT: Well, you know, surprisingly, this is still somewhat controversial. Almost certainly whatever was happening, however, was exclusive. You know, ordinary people almost certainly did not go up there and were not allowed to go up there and probably wouldn't have wanted to go up there.
BRIGGS: But ordinary people did have a role in shaping the Mississippian way of life. Tim says it all revolved around water. The city had sprung up because Cahokia had rain and corn, and people wanted to keep it that way. So huge crowds flocked to rituals that marked lunar cycles and made offerings for more rain. Cahokians also used water in ritual steam baths—a practice that survives today in the form of traditional sweat lodges.
There’s evidence that people spread this Mississippian religion up and down the river, kind of like missionaries. And apparently outsiders were drawn to Cahokia too.
PAUKETAT: People are clearly both, you know, making pilgrimages there but also moving in. And again, it includes people from as far away as Wisconsin, as far away as Mississippi.
BRIGGS: Cahokia’s people left behind artwork and oral histories but no written records. So it’s taken some detective work to figure out what happened next. What we do know is that just a few hundred years after it appeared, Cahokia was essentially abandoned.
PAUKETAT: So only really a century into this experiment, you see the first signs of difficulty. And that—you see those signs in part because some of the farmers who live all around the city, some of those farmers leave.
BRIGGS: According to Tim, people gave up on Cahokia for the same reason they first moved there: rain. Again, the climate changed slightly. This time it became drier. There wasn’t enough corn to support the booming city’s population. There’s also evidence that Cahokia built new defensive walls, so maybe war drove people away too. Either way, by the 1300s, the people of Cahokia began to leave.
PAUKETAT: The core of the city remains occupied all the way to the end, but the periphery, it starts—you know, they start shrinking. And the city, you know—the outer neighborhoods get abandoned first. And then you end up right in the very middle, there is an attempt to save the—to stop the seepage or stop the depopulation process for a while.
BRIGGS: Over time, American Indians returned and started new villages. But the grand city was gone forever. Mississippian culture spread across the eastern U.S. Today, several tribes, including the Osage, the Chickasaw, and the Peoria, trace their ancestry back to the people who built Cahokia. Andrea Hunter says the site needs to be protected.
HUNTER: For me, and when we take our Osage constituents there, we can really connect to that location. There are strong feelings because there's so many of our ancestors that are buried there. It's a very special visit when we go. Our community members can connect to that and feel that.
BRIGGS: But preserving that heritage isn’t easy. Coming up: how Andrea is fighting to save pieces of Osage culture that date back to Cahokia.
More after the break.
Today Cahokia Mounds is an Illinois state heritage site. Modern life creeps in, though, around the edges, like the neighboring flea market and highway construction facility—not to mention the busy road that runs in between the mounds. But you can still climb the 156 steps to the top of Monks Mound, look across at the other mounds, and sense how vast Cahokia must have been.
HUNTER: I know a lot of people may be aware of Cahokia, which is across the Mississippi River, over in Illinois. But, you know, that culture expanded not just from the mounds on that side.
BRIGGS: When French settlers began building St. Louis, there were at least a couple of dozen mounds in the city itself, plus maybe hundreds more in surrounding areas. And it’s not like they were tough to notice. Settlers nicknamed St. Louis “mound city.” Many of those mounds survived into the 1800s. The biggest, named Big Mound, was 30 feet tall and almost as long as a football field. But workers tore it down because they wanted the dirt for railroad construction. By 1869, there was nothing left of Big Mound—just photographs.
The same thing happened over and over: destroying Mississippian mounds in the name of so-called progress. Leading up to the 1904 world’s fair, the city government demolished 16 mounds, all at once. Now there’s just one left: Sugarloaf Mound.
HUNTER: The ultimate goal is that we can share our history with the community there in St. Louis.
BRIGGS: But these mounds aren’t only symbols from the past. Many of them are burial mounds, so Andrea wants to appropriately remember the people buried there. The hard part is that many sites the Osage consider sacred are now on privately owned property. So in the fight to save these sites, Andrea has embraced real estate: buying back ancestral lands, piece by piece.
HUNTER: It's not that we're wanting to go out and buy property, but … we do.
BRIGGS: Since the 1920s, Sugarloaf Mound has been privately owned, with a house sitting right on top of it. In 2008, Andrea got big news. The owners were ready to sell the upper tier of the mound. Andrea wanted the Osage Nation to scrape together the money—a little over a quarter million dollars—to buy it for themselves. But some members of the Osage legislature were skeptical.
HUNTER: You know, that was an interesting process because, you know, like with any community, you've got people with varying ideas about our history and what's important. You know, should we be purchasing property in another state, even though it's our former ancestral lands? It was a struggle to make that commitment as a whole, as a tribe.
BRIGGS: Andrea gave presentation after presentation to make the case that Sugarloaf Mound is a part of Osage history. It took nine months, but the Osage government agreed to buy the property.
HUNTER: Oh my gosh. I was just ecstatic about it because it seemed like it took forever, even though it was just a matter of months that we went through this process. You know, when we finally secured the property, and I was just—oh my gosh, I was beside myself. I was so happy about it.
BRIGGS: After they secured the property, the Osage removed the house. Andrea could finally explore long-standing questions about Sugarloaf Mound—like, why did people build it?
HUNTER: There have been speculation that it could have been a burial mound, so we were very interested in trying to determine whether it was a burial mound or not.
BRIGGS: Since it’s a sacred site—plus she doesn’t want to risk disturbing human remains— digging is out of the question. Instead, she tried ground-penetrating radar, a device that sort of gives you x-ray vision below the surface. At first, there were no signs of human remains.
HUNTER: But what we did find was a very interesting anomaly on one portion of the conical mound. It was kind of an oval—circular—anomaly that was very strong.
BRIGGS: This anomaly was about three feet wide and maybe a foot-and-a-half below the surface. It’s not clear what it is, but it could be the remains of a huge fire on top of the mound. Andrea also determined that the top of Sugarloaf Mound has a direct line of sight to Monks Mound at Cahokia. And in another direction, Sugarloaf looks out on a bend in the river that a person standing at Monks Mound wouldn’t be able to see. So Sugarloaf Mound may have been an outpost where people used smoke to communicate with central Cahokia.
HUNTER: For instance, if somebody—some group were coming up the Mississippi River, this could have been a signaling site where we informed Monks Mound.
BRIGGS: Andrea’s radar wasn’t powerful enough to penetrate all the way through the mound. She hopes to go back with a stronger instrument and look for more clues. In addition to studying the mound, the Osage Nation also has to actively protect it. Andrea says people sometimes trespass at night, so they put barriers in the driveway.
HUNTER: Well, that didn't keep people out, so we decided we needed to fence the property and put up security cameras. So we did that, and that helped. But it's still—people were coming on the property, and at one point we had an individual spray-painting graffiti on the house.
BRIGGS: The purchase of Sugarloaf Mound shows that it’s possible to put Indigenous sites back in the hands of Native descendants. But that’s just one. Andrea says there could be thousands out there, and she’s always looking for more.
HUNTER: It's a rare instance when one of these properties does come to our attention—that it's for sale.
BRIGGS: But in 2021, that happened. One of those sites did come up for sale. This one isn’t a mound but a shrine inside a cave. This shrine is another remnant of Cahokia, and it’s so important that Andrea calls it the single most sacred Osage site. It’s called Picture Cave, and it sits on privately owned land, nearly 60 miles west of St. Louis. And its owners decided to put it up for auction.
JIM DUNCAN (ANTHROPOLOGIST): It makes the hairs stand up on the back of your neck when somebody tells you they're going to auction that cave.
BRIGGS: This is Jim Duncan. He’s an anthropologist and former director of the Missouri State Museum. He’s one half of a husband-and-wife team that researched Picture Cave for two decades. Jim also has Osage ancestry, although he’s not an enrolled member of the tribe.
Around 1990, a couple of people approached Jim and his wife, Carol Diaz-Granados. They were amateur archaeologists—more like collectors—and they said they had discovered magnificent rock art. Carol had tons of experience with local rock art, so she asked to see the evidence.
CAROL DIAZ-GRANADOS (ANTHROPOLOGIST): Drawings—line drawings of the images in Picture Cave—some of the more spectacular images. And they were so spectacular that we took it with a grain of salt. We just couldn't believe that such detailed drawings existed.
BRIGGS: So they went to see it for themselves. Now it’s not an easy approach to get to the rock art. This isn’t a cave where you can just walk right in. You start off crawling on your hands and knees.
DIAZ-GRANADOS: And then for me, I have to turn over on my stomach and scoot back until—and reach down with one foot to touch a pointed rock blindly with one foot. Then I can sort of lower myself down to the next big step off. Thank heavens I've never fallen, but it's easy to fall.
BRIGGS: Inside, drawings cover the walls. They’re not that big, mostly around six inches high. But there’s a lot of them—roughly 400. The drawings show humans and animals and also some fantastical creatures, like a fanged water spirit that’s part serpent with deer antlers.
DUNCAN: And it's a narrative that's going on in there with backstories, and it's a very complex narrative. But all the depictions—the characters on the walls of that cave are supernatural beings.
BRIGGS: Chemical dating shows that the cave paintings are a thousand years old. So this narrative would have been painted shortly before the birth of Cahokia by the same Mississippian people. With permission from the cave’s owners, Carol and Jim went back there over and over to document the artwork. Jim also worked with Osage elders to learn more about the cave’s importance.
DUNCAN: The Osage recognize it for what it is: It's the womb of the universe. Now if you can do any better than that without going to Rome and standing in the square at St. Peter's, you tell me about it.
BRIGGS: When was the last time you were in the cave?
DIAZ-GRANADOS: Oh boy. That was before my first knee replacement. Yeah, that's been several years. I do not intend to ever go back into that cave, and I made that decision some years ago, not just because of artificial knees. But I think the cave is extremely dangerous. I think it's fragile. It has collapsed once before in the past. The whole center section of that cave is collapsed. That central collapse to me is a warning. It happened before. It can happen again.
BRIGGS: When the family who owns the cave decided to put it up for auction, Andrea Hunter snapped into action. She’s never been inside the cave herself. But just like Sugarloaf Mound, she wanted the Osage Nation to own another piece of its history. But at Picture Cave, the story ended differently. In September 2021, an anonymous buyer paid more than two million dollars for the cave and a parcel of surrounding land.
HUNTER: Unfortunately we were not successful at the auction for Picture Cave. So that was—that was really hard. Now we have no idea what is going to happen to it.
BRIGGS: The sale of Picture Cave made national news. And for Carol and Jim, it was a painful blow. Even though they’ve known the old landowners for years, they were blindsided by the sale. They found out secondhand just before it happened.
(To Diaz-Granados) What effect do you think this sale has on the overall effort to preserve Indigenous culture in the area, or even in the entire country?
DIAZ-GRANADOS: Yeah, that’s bad. It really sends a bad message. I don't know how else to put that. It sends a very bad message that sacred American Indian sites can be bought by anybody—can be bought by anybody. That's not right. That's just not right. There's a difference between right and wrong, and that is not right.
BRIGGS: But Andrea Hunter isn’t admitting defeat. She’s hopeful that the new owner of Picture Cave will be open to working with her, like another Missouri landowner did recently.
HUNTER: The day after the auction for Picture Cave, we had a signing ceremony here. Chief [Geoffrey] Standing Bear received the deed for a piece of property on the western side of the state of Missouri.
BRIGGS: Outside of Kansas City, a landowner had discovered burial mounds on their property, and they donated the land to a Native rights group. That group gave the ancestral lands—20 acres of it—back to the Osage. And there could be more donations coming. Andrea says she’s in talks to recover 80 acres in another part of Missouri.
Ultimately, she wants to keep the Osage legacy alive. She hopes to build an educational center at Sugarloaf Mound so that people can learn a chapter of American history they may not know about.
HUNTER: We want the folks to know about the extent of the culture that was there—that was really a magnificent culture that had far-reaching trade networks and a massive political and religious system that was in place.
BRIGGS: The work at Sugarloaf Mound moves us closer to this fuller picture that Andrea describes. The Mississippian heritage imbued in these sites—whether it's the big ones like Cahokia, the smaller ones like Sugarloaf, and everything in between—taken together, they’re beginning to reveal more of the complex history of these ancient Americans.
And the people who made that happen? They may not live in the same place, but they sure didn’t go away.
If you like what you hear and want to support more content like this, please rate and review us in your podcast app, and consider a National Geographic subscription. That’s the best way to support Overheard. Go to natgeo.com/explore to subscribe.
And if you want to know more about Cahokia, check out our show notes. There’s an article from National Geographic History magazine with pictures of artifacts from Cahokia and reconstructions of life in America’s first city. Also, Cahokia is also featured in a new book from National Geographic. It’s called Lost Cities, Ancient Tombs: 100 Discoveries That Changed the World. You can read about archaeological finds on six continents that shed light on humanity’s past, going back millions of years.
We also have a story about new research that sheds light on why Cahokia was abandoned. And meet an Osage photographer who has a message about American Indian culture. He says, “The state of things is not in decline.” That’s all in the show notes, right there in your podcast app.
Overheard at National Geographic is produced by Jacob Pinter, Brian Gutierrez, Ilana Strauss, and Marcy Thompson. Our senior editor is Eli Chen. Our senior producer is Carla Wills. Our executive producer of audio is Davar Ardalan. Our fact-checkers are Julie Beer and Robin Palmer. Our copy editor is Amy Kolczak. Hansdale Hsu sound-designed this episode and composed our theme music.
This podcast is a production of National Geographic Partners. The National Geographic Society is committed to illuminating and protecting the wonder of our world and has funded the work of National Geographic Explorer Tim Pauketat.
Whitney Johnson is the director of visuals and immersive experiences. Susan Goldberg is National Geographic’s editorial director. And I’m Amy Briggs. See you next time.
Learn more about Cahokia—and see depictions of America’s first city, as well as artifacts left behind—in National Geographic History.
See more stunning finds that unlock our deepest history in the new book Lost Cities, Ancient Tombs: 100 Discoveries That Changed the World. Subscribers can read more about the two centuries of excavation on six continents that give voice to humanity’s forgotten past.
Why did people abandon Cahokia? New research rules out a theory that environmental degradation led to its demise and shows the limits of using a modern, Western lens to study the ancient city.
Learn more about Picture Cave—the Osage “womb of the universe”—in the book Picture Cave: Unraveling the Mysteries of the Mississippian Cosmos by Carol Diaz-Granados and Jim Duncan.
Osage photographer Ryan RedCorn has a message about American Indian culture: “The state of things is not in decline.”
Grisly discoveries of unmarked graves at U.S. and Canadian boarding schools have forced a reckoning over government-funded programs that were designed to strip Native American children of their language and culture—and even their names.
If you like what you hear and want to support more content like this, please consider a National Geographic subscription. Go to natgeo.com/explore to subscribe today.