Cahokia Mounds, in southeastern Illinois, was once a thriving American city…before there was an America. During its peak–about 1100 A.D., the population was larger than London’s at the same time. Until 1800, no other urban area in the United States would surpass its area size or population of 20,000–when Philadelphia boomed and hit 30,000 residents.
It’s easy to miss the significance of this area, with its grassy spaces and a few stubby hills. It certainly doesn’t look historic enough to be a UNESCO site of Scientific and Cultural importance. But about the time the Mayan civilization in Mexico was collapsing, and Europe was stuck in the Dark Age, this spot was a thriving city with neighborhoods, markets, festivals, and leisure activities.
Location, location, location…Cahokia Mounds had it all
Today you can look across the Mississippi River and see St. Louis. Over 1200 years ago, with the river on one side and numerous creeks on the other, it would have been hard to find a more perfect place to establish what would become the only “first-line community” of this Indigenous American culture–permanent and complex–even though the culture sprawled across the Midwest and Southeast.
Cahokia sat where the Mississippi, Missouri, and Illinois rivers converge in a magnificent fertile zone called the American Bottom. Spring rains delivered the silt from rushing water to the fields. Fish were abundant, and so were birds and animals that could feed on the lush plants. The network of waterways made travel easy.
The nearby Ozark Mountains supplied rocks, minerals…and deer, the main source of meat, plus skin for hides. The Prairies provided building materials. The Woodlands were a constant source of trees, wildlife, berries, and salt licks, for humans and animals.
The inhabitants and architects of Cahokia Mounds weren’t the first to “discover” the abundance of the area. There’s archeological evidence that humans arrived around the end of the Ice Age, about 10,000 B.C. In fact, the Mounds were later built over earlier structures.
How did Cahokia get its name?
The culture didn’t have a written language, so we don’t know what the inhabitants called their city. It didn’t have a name until 17th-century French explorers decided on “Cahokia,” based on a tribe that inhabited the area at that time.
The indigent people who established the city have been called “Mississippians” by archeologists, with a timeline to identify the stages of progress.
- The Late Woodland Era (600-800 A.D.) Apparently, there were also Early and Middle Woodland Eras that consisted of scattered shelters and small homesteads. Immigration in North America eventually led early Native Americans to discover this area that was rich in everything they needed to permanently settle: fertile soil, fresh water, forests, and a hospitable climate.
- Emergent Mississippian Era (800-1000 A.D.) A growing dependence on agriculture–mainly corn–meant that the culture had to specialize to accommodate its expanding society. Farmers, hunters, toolmakers, carpenters, craftspeople, artisans…just like today Homes were built in residential areas, based on a class system, complete with plazas and courtyards. And what’s a society without politicians and religious leaders? Yep, those roles evolved, too. This is when the mounds are started.
- Mississippian Era (1000-1400 A.D.) Cahokia at its peak! The city covered six square miles, complete with suburbs. The mounds are finished, each with a shape based on its purpose. There are rituals around life events, including human sacrifices. Beautiful artwork is created. Trade flourishes: copper from the Upper Great Lakes, seashells from the Gulf of Mexico.
Now, about those “Mounds”
There were 120 mounds at the Cahokia site, the first ones dating back to about 900 A.D. (About 80 remain.) Such quantities of earth had to be transported to build the mounds that quarries were dug, called “borrow pits.” Some of the quarries were used as refuse dumps; others filled with rain and became fish farms. The mounds had to be rebuilt or modified over time. A few were built over older mounds.
The first mounds were quickly followed by others, constructed in three different shapes, each shape dedicated to a ceremonial purpose:
The most common type of mound, these are rectangular or square, with sloping sides. They have a flat top for important structures such as a temple or housing for the leaders. Monks Mound (named for the French Trappist Monks who built their monastery and a chapel on the spot in the 1700s) was the largest. When the monks arrived, the Illiniwek tribe had a small village on the lowest level.
Monks Mound was clearly the most important mound at Cahokia. It was the highest platform, with an enormous plaza area in front of it. Atop the mound was an enormous structure, a palace or a temple. Excavations show it was 104 feet long, 48 feet wide, and about 50 feet tall. Citizens carried 22 million cubic feet of dirt in baskets to make the mound, dug with stone tools.
Monks Mound was enlarged several times over the centuries to accommodate the evolving culture. Nothing was done haphazardly; soil samples show that the engineers used various types of soil and stone to ensure stability and proper drainage. Cahokia Mounds was built and maintained by people with knowledge of scientific principles.
The purpose of the conical mounds isn’t fully known, although they seem to be related to burials for high status citizens or to mark significant locations. (Big difference, I know.) They were much shorter and smaller than platform mounds, and often paired with them. Seems that the small platform mounds served as charnel houses to prepare bodies after death and the conical mounds for burials. Only a few have been excavated, so there’s still much to learn. (But we do know that ordinary folk were buried in cemeteries.)
Because no one really knew much about these pointy piles of dirt scattered around, the conical mounds slowly disappeared or became rounded from erosion. Farmers leveled them, highways removed them, subdivisions replaced them. Landscapers used the soil to create modern yards and gardens. Some are barely visible now. The remaining conical mounds can be up to 40 feet high.
Now we come to the archeologist’s “dream mound.” There are six of them at Cahokia, located at the city’s borders. They were built in a wide range of sizes; the largest, called Powell’s Mound (Mound 46) was 310 feet long, 180 feet wide, and 40 feet tall. Sadly, it was destroyed in 1931 to use to its soil to level a patch of low land at a nearby farm.
We can only imagine what giant Mound 46 held, because between 1967-1971, the little Mound 72 revealed incredible discoveries. First, mass graves with 118 females between the ages of 12-25, indicating human sacrifices during the peak years of Cahokia; one grave held 53 remains. Next, a grave with four males whose heads and hands had been removed.
Finally, the burial site of a male and a female, in their 20s, who had been laid out on a blanket of 20,000 marine shell beads. Obviously leaders or royalty, they were surrounded by bodies of servants, and objects for their afterlife: 800 perfect arrow points, games, mica from the Appalachians, and copper sheets from the Upper Great Lakes.
Serving a dual purpose, ridge-top mounds were located at the borders of Cahokia, possibly serving to mark the city’s boundaries.
Stockades to keep people in…and out
As the city and surroundings grew, protection–and defense–became essential. And because Cahokia Mounds was a class-based society, the elites wanted to create a barrier between themselves and the “others.” (Some things never change…)
Stockades were built to surround important structures and areas. The logs were 15 feet tall, and a foot in diameter, hauled by Cahokians without the benefit of wagons. Over time, four stockades were built, five logs deep. Each stockade required 15,000-20,000 oak or hickory trees.
Woodhenge: Take that, England!
About half a mile west from Monks Mound is a large circle discovered in 1961 when preliminary investigations for a proposed highway began. One circle turned out to be five circles, each a little larger than the previous. The edges were dotted by pits that once held cedar posts.
Like famous Stonehenge, the posts align with the sun at the Spring and Autumn Equinoxes, indicating the change of seasons: when to plant and when to harvest. The posts were also positioned to see the sun rise over the top of Monks Mound, where the Chief likely lived; he was considered to be the brother of the Sun.
Woodhenge also served as a lunar marker and possibly to indicate directions. The first circle was built around 950 A.D. Each circle increased by 12 poles: 24, 36, 28, 60…the fifth circle wasn’t completed, but would have been 72. Experts guess the circle became bigger as Monks Mound was enlarged and the city grew. A small platform mound, Mound 44, is nearby; the home of the Sun priest may have been located there.
Oh, and that highway? It got rerouted to avoid Woodhenge and further destruction of Cahokia Mounds.
America’s first city is abandoned…but why?
Sometime around 1250, the city and area began a steady decline. Archeologists and historians are puzzled to figure out why the Cahokians abandoned their homes and land in 1400. There is no sign of invasion or destruction from war. No known natural disasters occurred.
Possible reasons for leaving the site include:
- Climate change that caused shorter growing seasons
- Disease that was brought back from the trade routes
- Political or religious conflicts and rebellions
The most common reason is that the Cahokians simply depleted their supply of just about everything. Forests were cut down, eliminating habitats for animals and plants. Nearby bluffs were stripped, causing silt to gather and block water flow and increase flooding. The other listed reasons may have contributed to the downfall, too, causing families to leave in search of a new place to live.
Ready to go to Cahokia Mounds? Here’s what to know!
Unfortunately, Cahokia Mounds isn’t as extensively excavated or displayed as other archeological sites you may have visited (thinking of Greece and Italy). But it’s definitely worth your while to spend time in the space and imagine how great the city once was. To get a sense of its size, watch this YouTube video.
I recommend checking the days and hours so you can see the excellent museum and interpretive center. In fact, I suggest going twice: Before, so you know what to look for, and After, so it makes more sense. The grounds are open from 8 a.m. to dusk. Print the trail map, in case the center’s not open when you arrive. You can also order the Self-Tour Guide online, for about $1.00.
Pro Tip: Bring bug spray and water. Wear sunscreen and a hat.
As I write this, in May 2022, the interpretive center is temporarily closed to get a new roof and ventilation system. Guided tours of the Mounds are given Wednesday-Sunday at 1 p.m.–register ahead, please. Download the brochure for history and more information.
Cahokia Mounds State Historic Site, administered by the Illinois Department of Natural Resources – Historic Sites Division, is just eight miles from downtown St. Louis near Collinsville, Illinois, off Interstates 55-70 and 255, and Illinois 111, on Collinsville road.
Address: 30 Ramey Street
Collinsville, IL 62234
What’s nearby? Casey, IL: Tiny Town, BIG Things!!