America's Forgotten City

Cahokia was born with a bang and died of unknown causes.

This story appears in the January 2011 issue of National Geographic magazine.

If they ever build a Wal-Mart at Machu Picchu, I will think of Collinsville Road.

I'm standing at the center of what was once the greatest civilization between the deserts of Mexico and the North American Arctic—America's first city and arguably American Indians' finest achievement—and I just can't get past the four-lane gash that cuts through this historic site. Instead of imagining the thousands of people who once teemed on the grand plaza here, I keep returning to the fact that Cahokia Mounds in Illinois is one of only eight cultural World Heritage sites in the United States, and it's got a billboard for Joe's Carpet King smack in the middle of it.

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Four centuries before Columbus arrived in the Americas, Indians in Illinois created a city with up to 15,000 inhabitants, more than a hundred earthen mounds, and far-reaching influence. What was this place we call Cahokia, and what happened to it?

But I suppose Cahokia is lucky. Less than ten miles to the west, the ancient Indian mounds that gave St. Louis the nickname Mound City in the 1800s were almost completely leveled by the turn of the century. Today only one survives, along with some photographs and a little dogleg road named Mound Street. The relentless development of the 20th century took its own toll on Cahokia: Horseradish farmers razed its second biggest mound for fill in 1931, and the site has variously been home to a gambling hall, a housing subdivision, an airfield, and (adding insult to injury) a pornographic drive-in. But most of its central features survived, and nearly all of those survivors are now protected. Cahokia Mounds may not be aesthetically pristine, but at 4,000 acres (2,200 of which are preserved as a state historic site), it is the largest archaeological site in the United States, and it has changed our picture of what Indian life was like on this continent before Europeans arrived.

Cahokia was the apogee, and perhaps the origin, of what anthropologists call Mississippian culture—a collection of agricultural communities that reached across the American Midwest and Southeast starting before A.D. 1000 and peaking around the 13th century. The idea that American Indians could have built something resembling a city was so foreign to European settlers, that when they encountered the mounds of Cahokia—the largest of which is a ten-story earthen colossus composed of more than 22 million cubic feet of soil—they commonly thought they must have been the work of a foreign civilization: Phoenicians or Vikings or perhaps a lost tribe of Israel. Even now, the idea of an Indian city runs so contrary to American notions of Indian life that we can't seem to absorb it, and perhaps it's this cognitive dissonance that has led us to collectively ignore Cahokia's very existence. Have you ever heard of Cahokia? In casual conversation, I've found almost no one outside the St. Louis area who has.

Our ignorance has deep roots. The first person to write a detailed account of Cahokia's mounds was Henry Brackenridge, a lawyer and amateur historian who came upon the site and its massive central mound while exploring the surrounding prairie in 1811. "I was struck with a degree of astonishment, not unlike that which is experienced in contemplating the Egyptian pyramids," he wrote. "What a stupendous pile of earth! To heap up such a mass must have required years, and the labors of thousands." But newspaper accounts of his discovery were widely ignored. He complained of this in a letter to his friend former President Thomas Jefferson, and with friends in such high places, word of Cahokia did eventually get around. Unfortunately it was not word most Americans, including subsequent Presidents, were very interested in hearing. The United States was trying to get Indians out of the way, not appreciate their history. Andrew Jackson's Indian Removal Act of 1830, which ordered the relocation of eastern Indians to land west of the Mississippi, was premised on the idea that Indians were nomadic savages who couldn't make good use of land anyway. Evidence of an ancient Indian city—one that rivaled the size of Washington, D.C., at the time—would have mucked up the story line.

Even American universities took scant notice of Cahokia and other homegrown sites before the second half of the 20th century. They preferred sending their archaeologists to Greece and Mexico and Egypt, where the stories of ancient civilizations were comfortably distant and romantic. The few people who championed Cahokia and its neighboring mound centers at East St. Louis and St. Louis fought a mostly losing battle against development and neglect for the better part of a century. The latter two sites—among the largest Mississippian communities in their own right—were destroyed and paved over. And though Monks Mound, named for French monks who once lived in its shadow, became a tiny state park in 1925, it was used for sledding and Easter egg hunts. The rest of Cahokia was largely ignored—built on and only sporadically studied—until the 1960s.

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A few miles from Cahokia in St. Louis, residents saw the city’s many mounds as little more than handy sources of soil. The largest, Big Mound, stood some 30 feet high and 300 feet long and took years to level. Oblivious to its historical value, workers needing fill dirt for a railroad bed carted off the last of it in 1869.

And that's when history demonstrated its fine sense of irony, because the biggest construction project to tear into Cahokia would also put it on the map. President Dwight Eisenhower's interstate highway program, though a massive undertaking that changed America's landscape as dramatically as the railroads once did, contained provisions for the study of archaeological sites in its path. This meant more money for excavations than had ever been available, as well as a clear agenda for where to dig, when, and how fast. With two highways slated to skewer the ancient city—I-55/70 now bisects Cahokia's north plaza, creating a road sandwich with Collinsville Road, a quarter mile to the south—archaeologists began to systematically study the site. What they found was nothing less than revelatory.

It became apparent that Cahokia was more than just a stupendous pile of earth or a cere­monial site where scattered tribes congregated once in a while. Nearly everywhere they dug, archaeologists found homes—indicating that thousands of people had once lived in the community—and many of these homes had been built within a very brief span of time. In fact, the whole city seemed to spring to life almost overnight around 1050, a phenomenon now referred to as a "big bang." People streamed in from surrounding areas, built houses, and quickly constructed the infrastructure of a new city—including several mounds with buildings on top and a grand plaza the size of 45 football fields, used for everything from sporting events to communal feasts to religious celebrations.

Making the story even more interesting was the clear evidence of ritual human sacrifice. Archaeologists excavating Mound 72, as they labeled it, found the remains of 53 women and one very high status man, as well as the decapitated remains of four men who may have been on the wrong side of some sort of authority. The discovery belied the common belief that American Indians lived in egalitarian communities without the sorts of often brutally maintained hierarchies that defined many other civilizations. Was Cahokia an empire, like the Mesoamerican civilizations to the south? It was too soon to tell, but something spectacular had happened here, and it became clear this was a mystery worth trying to solve.

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A ten-story behemoth known as Monks Mound is the centerpiece of the 2,200 acre Cahokia Mounds State Historic Site. Eighty surviving mounds dot this cultural World Heritage site; some were used as building platforms, some for burials.

If you want to understand Cahokia, the first thing you've got to do is climb the 156 steps to the top of Monks Mound. From the flat top of this colossus—with a footprint of 14 acres, it is larger at its base than the Great Pyramid of Khufu, Egypt's largest—you not only get a sense of how much labor went into its construction, but you can also understand why it might have been built in the first place. From here you can survey Cahokia's domain: the vast floodplain known as the American Bottom, stretching from St. Louis to a long line of bluffs three miles east of Cahokia and as far to the north and south as the eye can see. After directing the construction of what would have been the highest geographic feature in the 175-square-mile floodplain, a chief or high priest would have had a bird's-eye view of the land under his sway.

Of course, that scenario presumes we know that Cahokia had such a single leader, which we don't. We don't even know what this place was called—the name Cahokia is borrowed from a tribe that lived nearby in the 1600s—or what the people who lived here called themselves. With no written language, they left behind the same scattering of meager clues that makes understanding prehistoric societies everywhere so challenging. (Pottery's fine and everything, but how much would a foreign culture really learn about us by looking at our dishes?) If deciphering the story of history is contentious, try coming to agreement on the story of prehistory. "You know what they say," says Bill Iseminger, an archaeologist who has worked at Cahokia for 40 years. "Put three archaeologists in a room and you get five opinions."

He's not exaggerating much. Even when Cahokia scholars agree, they tend to frame their positions so it seems like they're disagreeing—but there are points of general consensus. Everyone agrees that Cahokia developed quickly a couple centuries after corn became an important part of the local diet, that it drew together people from the American Bottom, and that it dwarfed other Mississippian communities in size and scope. The battle lines tend to form along the questions of how populous it was, how centralized its political authority and economic organization were, and the nature and extent of its reach and influence.

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Placid in the morning mist, the plazas surrounding Monks Mound teemed with thousands during construction, which required 15 million baskets of soil. A large temple or palace was built on top, perhaps serving as center stage for religious ceremonies.

At one extreme you have descriptions of Cahokia as a "theater of power," a hegemonic empire sustained by force that reached deep into the Mississippian world and perhaps connected to Mesoamerican civilizations such as the Maya or Toltec. At the other extreme you have characterizations of Cahokia as little more than an especially large Mississippian town whose residents had a talent for making big piles of dirt. But as usual, most of the action happens in the middle area between those poles.

Right now the discussion is being spearheaded by Tim Pauketat at the University of Illinois, who with his colleague Tom Emerson argues that Cahokia’s big bang was the product of a visionary moment: A leader, prophet, or group cast a vision for a new way of living that attracted people from far and near, creating a rapidly expanding cultural movement.

When I meet Pauketat at Cahokia to see the site through his eyes, he's more interested in showing me what he's found in the uplands several miles to the east: signs that Cahokians held sway over outlying laborer communities that supplied food to the city and its elites—evidence, Pauketat argues, that Cahokia's political economy was centralized and broad reaching. This is a controversial theory, because the research supporting it hasn't been published yet, and because it goes to the heart of the argument about just what kind of society Cahokia was.

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Artifacts from Cahokia and elsewhere reveal a broad network of trade in goods and raw materials, including copper from the Great Lakes region, and shells from the Gulf of Mexico (bottom, far left). Chunkey, a popular sport using rolling stones (top, left), was played throughout the Mississippian region.

Gayle Fritz at Washington University in St. Louis says that if Cahokia was a city, it wasn't the kind we usually think of, but one full of farmers growing their own food in nearby fields. Otherwise there would be more signs of storage facilities. It's this sort of practical limit on the size of a subsistence-based agricultural community that leads minimalists like Penn State's George Milner to argue that population estimates for Cahokia—currently ranging between 10,000 and 15,000 for the city proper and another 20,000 to 30,000 in the surrounding areas—are inflated by a factor of two or more and that characterizations of Cahokia as something like a protostate are way off base. But with less than one percent of Cahokia excavated, speculation by every camp remains in higher supply than evidence. Washington University's John Kelly, a longtime stalwart of Cahokian archaeology, sums up the present understanding of Cahokia nicely: "People aren't really sure what it is."

Nor do people know what happened to it. Cahokia was a ghost town by the time Columbus landed in the New World, and the American Bottom and substantial parts of the Mississippi and Ohio River Valleys were so depopulated they are referred to as the Vacant Quarter. Cahokia's demise is perhaps an even greater mystery than its emergence, but there are a few clues. The city grew to prominence during an especially favorable climate phase and began shrinking around the time the climate became cooler, drier, and less predictable. For an agricultural community dependent on regular crop yields, the changing conditions could have been anything from stressful to catastrophic.

The fact that between 1175 and 1275 Cahokia's inhabitants built—and rebuilt, several times—a stockade encircling the main part of the city suggests that conflict or the threat of conflict had become a standard feature of life in the region, perhaps because there were fewer resources. Furthermore, dense populations create environmental problems as a matter of course—deforestation, erosion, pollution, disease—that can be difficult to counter and that have been the downfall of many a society.

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The last Indian mound in St. Louis finally has a guardian. After a year on the market, Sugar Loaf Mound was bought by the Osage, one of several tribes who claim Cahokians as ancestors. Their plan: Remove the house and restore a memory.

That Cahokia lasted for only some 300 years, and was at the peak of its power for half that at most, should not come as a surprise. "If you look broadly at human history, failure is the norm," says Tom Emerson. "What's amazing is when things last."

Emerson is currently heading a huge excavation in East St. Louis of Cahokia's next-door neighbor, a site that had thousands of residents of its own (sort of like Fort Worth to Cahokia's Dallas). And again, road construction is paying the tab: A new bridge across the Mississippi is giving Emerson's team a crack at 36 acres that had been lost to earlier progress, if you can call the twisted path of human history something as simple as "progress." The stockyards that were built on the ruins of this Mississippian settlement have been shuttered for years, casualties of East St. Louis's own decline from a vibrant city to a collection of vacant lots and boarded-up buildings. This is history's march in our own midst: fleet of foot and easy to miss.

When I drive to St. Louis to see if anything still memorializes the big mound (named, with an appropriate lack of imagination, Big Mound) that was destroyed there by 1869, I'm surprised to see that the exact spot where it was located is where the new bridge from East St. Louis will land. I ask around and learn that archaeologists excavated this lot too before construction started. But they didn't find a trace of Big Mound, only remnants of the 19th-century factories that had taken its place. That is now the accessible history of this site. The rest is gone.

After a failed first attempt, I do finally locate a marker for Big Mound. It's a little cobblestone memorial a half block down Broadway from Mound Street, with a missing plaque and grass growing between its rocks. As luck would have it, I find it just as a man arrives to spray it with weed killer. I ask him if he works for the city, and he says no. His name is Gary Zigrang, and he owns a building down the block. He's called the city about the marker's disrepair, and they haven't done anything, so he's taking matters into his own hands. And as he sprays the weeds on the forgotten memorial for the forgotten mound of the forgotten people who once lived here, he says, "What a shame. There's history here, and it needs to be taken care of."

Author Glenn Hodges is a former staff writer for National Geographic. Photographers Ira Block and Don Burmeister are based in New York City.