ON A CLEAR DAY, if you climb the 144 steps to the top of Monks Mound in Southern Illinois, you can make out the skyline of St. Louis, a bustling modern city. But had you climbed those stairs 700 years ago, you would have been standing at the heart of a sprawling ancient metropolis called Cahokia—one of the largest pre-Columbian settlements of its time—with public plazas, places of worship, a complex network of roads and courtyards, and even an astronomical observatory.
The cultural, religious, and economic center of Mississippian culture, Cahokia was once home to as many as 20,000 people, a population that rivaled many European cities of the time. The population of “Greater Cahokia,” a collection of outlying farms and villages, seems to have peaked at around 50,000 sometime around 1100 A.D. Religious festivities, days-long festivals, and raucous sporting events filled the townsfolk’s lives.
But just 250 years later, Cahokia was abandoned, the grass on its 120 earthen mounds growing tall and untended. Researchers are still trying to figure out why. Some have proposed that Cahokia’s inhabitants used up the area’s natural resources, overhunting and deforesting the land surrounding the major city. Others have hypothesized that frequent droughts and floods doomed the city, while some theories center around the arrival of political unrest, outsiders, or disease.
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| Archaeologists excavating a Native American garbage dump in Monk’s Mound circa 1972, Cahokia Mounds State Park, Illinois. -getty images |
CAHOKIA WAS STRATEGICALLY LOCATED at the confluence of the Missouri, Mississippi, and Illinois Rivers in a fertile region known as the American Bottom.
For a while, Cahokia was an ordinary-sized settlement, but around 1000 A.D., agriculture—especially corn—became a food staple for Native tribes, transforming nomadic societies into more permanent settlements. It was during this time that Cahokia, with rich soil and easy access to water, underwent its “big bang,” drawing new residents from many Mississippian cultures: the Natchez, the Pensacola, the Choctaw, and others. In fact, when archeologists analyzed teeth found at the site, they discovered that immigrants from other places made up about one-third of the population.
With its population booming, Cahokia quickly became more than just a large, agrarian community, but soon transformed into a government, commercial, and religious capital as well. Topping out at about nine square miles, Cahokia soon had 120 earthen mounds inside its borders.
The city received the name Cahokia hundreds of years later after the French arrived to the area in the 17th century and were greeted by the Cahokia Nation, a tribe in the Illinois Confederation. However, scholars believe that the tribe likely did not inhabit the city during its heyday.
BECAUSE THE PEOPLE OF CAHOKIA left behind no written records—and because its inhabitants dispersed long before Europeans arrived—knowledge about what life was like in the city has come primarily from archaeological investigation.
The presence of certain interior fortifications suggests that there was a social hierarchy in Cahokia. The city’s largest mound, Monk’s Mound (named by French Trappists in the 1800s), held a large building where Cahokia’s political and spiritual leaders convened. At its base, a town center—surrounded by a perimeter wall two miles in circumference—would have been the site of religious celebrations and ceremonies.
There is evidence that those ceremonies and celebrations could get pretty rowdy. Cahokians regularly imbibed “black drink,” a concoction made from the leaves of a holly tree with a caffeine content six times that of strong coffee, and archeologists have excavated waste pits that contained as many as 2,000 deer carcasses, seemingly from one massive rager.
Everyday life was busy for most Cahokia residents. Men hunted, farmed, and cleared land for wood; women tended the home, made pottery, and wove textiles. Most homes were on the other side of the perimeter wall, single-room abodes that were connected via intricate and well-planned courtyards and pathways. In fact, Cahokians plotted out an east-west road that still serves as the current-day route to St. Louis.
The many mounds that dotted Cahokia were used as burial sites, some for mass graves. Archeologists have stumbled upon a few that contain evidence of ritualized human sacrifice. Others—with skeletons featuring bashed skulls, decapitations, and projectile wounds—indicate political violence. It’s just one of many tantalizing clues that point to the mighty city’s eventual downfall.
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| A walking path surrounds Mound 59, one of the Twin Mounds at Cahokia Mounds State Historic Site in Collinsville, Illinois. - getty images |
CAHOKIA’S POPULATION PROBABLY PEAKED around 1100 AD, according to AJ White, a molecular archeologist at California State University, Long Beach, who has studied the area by analyzing its ancient poop. White and his colleagues analyzed sediment cores taken from nearby Horseshoe Lake for fecal molecules, finding that “the eleventh century showed the highest populations, and the lowest in the fourteenth,” he says. “In fact, almost 1400 on the dot, the population bottoms out.”
So, how did a thriving ancient metropolis of some 50,000 wither away so suddenly? There are a few prevailing theories.
Pointing to evidence of Cahokia’s cultural diversity—as well as human remains that suggest political violence—some scholars argue that internal dissension could have led to the city’s demise. Alternatively, trouble could have come from outside. In any case, between 1175 and 1275 A.D., the perimeter wall was rebuilt four times, indicating some conflict with neighboring tribes.
Another theory is that Cahokia simply ran out of natural resources; the perimeter wall alone would have required 20,000 logs. Beyond the wood needed for large, communal projects, individual residents would have required a consistent supply of wood for building, heating, and cooking. Not only would widespread deforestation have a deleterious impact on life in Cahokia, but it would also have changed the immediate ecosystem, as the denuded ground would have lost the ability to hold water, meaning more runoff and flooding in the region. While this theory has been popular for more than three decades, recent excavations have found no evidence of erosion or unstable soil during the reign of Cahokia.
Perhaps the most popular explanation for Cahokia’s abandonment is the occurrence of natural disasters like floods and droughts. Some scholars have demonstrated that Cahokia emerged during a time of reduced flooding and that its decline followed the return of large floods. Events like these, they argue, would have likely triggered crop failures, devastating the large city.
White’s scholarship supports this theory. Those sediment cores he analyzed for fecal molecules also showed evidence of periods of floods and drought, which coincided with “a big drop off” in population. “Climatic events such as droughts and floods likely played a role in the depopulation of Cahokia,” the archeologist says.
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| Small hamlets of wattle and daub houses were scattered over the fertile river plain around Cahokia. These were the homes of the farmers who supplied the city with food. In their fields they grew maize, beans, and squash. They stored their surplus crops in pits dug in the ground outside their houses. |
IN JULY, RESEARCHERS WHO ANALYZED carbon isotopes left behind by plants growing during the occupation of Cahokia published a paper challenging the theory that drought would have had a calamitous impact on the city of Cahokia.
“Our study combined with decades of research about the diversity of Cahokia crops and other food sources, makes us skeptical that food shortages played a decisive role in the abandonment of the city,” Bureau of Land Management archeologist Caitlin Rankin says in an email. Rankin argues that even if a drought did impact agriculture in the region, the farmers of Cahokia grew at least eight different crops, and residents “had access to an enormous freshwater fishery, one of the great flyways of the world, perennial wetland plants, and ‘food forests’ full of nuts and fruits that had been shaped by local communities for millennia,” meaning it would have been difficult for them to go hungry.
“This doesn’t mean that it might not have affected other parts of the landscape, including some of the places where they grew food. It also may have destabilized the region even if it didn’t cause crop failure at Cahokia,” Rankin explains.
White echoes this conclusion. Repeated floods and droughts likely “shocked the system,” he says. “It would have affected some people more than others, but anytime you have a disruption of the status quo—you’re likely to see change.”
While the mystery is far from solved, it’s possible that the inhabitants of Cahokia merely drifted away over time as the area became less hospitable, much like people today in parts of the world especially affected by climate change. This could mean that Cahokia died not by the bullet of one smoking gun, but rather by 1,000 cuts.
“This was a really complicated place, and there’s likely a really complicated explanation,” White says. “We need to figure out how we can unite all these different data—agricultural, economic, cultural, climatic. Societies deal with all these things at once, and a change in one can rock all the others.”
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