Cahokia: The Largest City North of Mexico Before Columbus

Just across the Mississippi from Saint Louis, on the Illinois side, sits a set of earthen mounds that most Americans drive past without a second glance. They should stop. What you are looking at are the remains of one of the most remarkable cities in the ancient world.

Cahokia at its peak, around the year eleven hundred, held somewhere between ten thousand and twenty thousand people, possibly more. That made it comparable to London at the same moment in history. It was the urban center of the Mississippian culture, a sophisticated agricultural civilization that built cities, conducted long-distance trade, and organized labor on a scale not seen again in this region for centuries after its collapse.

The central monument, Monks Mound, rises one hundred feet above the surrounding plain and covers more than fourteen acres at its base, larger in footprint than the Great Pyramid at Giza. It was built entirely by hand, basket-load by basket-load, over the course of roughly three hundred years. The effort required would have demanded a centralized authority, organized labor, and a surplus food supply. Cahokia had all three.

At the city's heart was a grand plaza covering more than forty acres, oriented with the cardinal directions, surrounded by wooden palisades and a ring of smaller mounds. The site contained at least one Woodhenge, a circle of wooden posts aligned to mark the solstices and equinoxes, suggesting an astronomical knowledge embedded in the city's sacred geography.

Around thirteen fifty, Cahokia was abandoned. Scholars debate why: climate change, soil depletion, political fragmentation, epidemic, or some combination. The people dispersed into smaller communities across the Midwest. Their descendants are thought to include the Osage and other nations still present today.

Cahokia Mounds is now a UNESCO World Heritage Site. It is the most significant pre-Columbian archaeological site north of Mexico, and it sits just off Interstate Fifty-Five, largely overlooked.