Ancient Cahokia of North America Reveals 900-Year-Old Treasures

While carrying out excavations at the site of North America’s first great city, which is called Cahokia by historians, a team of archaeologists and students from Saint Louis University unearthed a virtual treasure trove of Native American artifacts and ruins dating back to approximately 1100 to 1200 AD.  

Located near the site of modern-day St. Louis, Missouri, Cahokia was constructed by the mound-building Mississippian culture, which gave the nearby river its name. The excavation team was digging just to the west of the Cahokia Mounds when they made their discoveries, which surpassed the modest expectations they had when they launched their explorations. 

In an excavation layer associated with the Sterling Phase of the Mississippian Period, the team members unearthed wall trenches and assorted structures that they quickly established were between 800 and 900 years old. They also recovered many pieces of ceramic pottery and tools known as microdrills that were mixed in with the rubble of the buried buildings. The archaeologists who organized the excavations were delighted to find so many significant artifacts from this particular time period.  

This was a transformational time for the people of the Mississippian culture, who were experiencing rapid population growth and dealing with the challenges this development caused. The artifacts and ruins that have been unearthed will be carefully studied in the coming months, to see what secrets they might reveal about a mound-building culture that first rose to prominence in the lands of the current United States more than 1,000 years ago. 

The Birdman tablet is an engraved stone tablet discovered in the 1970s from Monks Mound at the Cahokia Mounds archaeological site. Believed to be associated with religious or ceremonial practices of the Mississippian culture, it has been adopted as the symbol of Cahokia Mounds. (Paul Sableman / CC BY 2.0) 

The Mississippian culture is best known for its earthen platform mounds, which were built several hundred years before European contact (in the late first millennium or early second millennium AD). Many of these mounds were destroyed by settlers who colonized the lands of the United States starting in the 17th century, but some have been preserved, and they can be found spread all over the central, eastern, and southeastern United States.  

In addition to their spectacular mounds the Mississippian people also built urban settlements, following the same pattern of cultural development and social organization as the great civilizations of Mesoamerica (i.e. the Maya, Inca, and Aztecs). The largest of all these settlements was Cahokia, which was built near the modern Mississippi River that bisects the United States running north to south.  

Cahokia was constructed in the ninth or tenth century AD, with expansion projects launched periodically after that. At its peak size it covered approximately six square miles (15 square kilometers) and was likely home to between 20,000 and 40,000 Mississippian culture residents. Building and land-use patterns were diverse, so houses, public squares and buildings, commercial establishments, temples and ceremonial centers, as well as farmland, were all included and intermixed within the city’s borders.  

Estimates are that approximately 120 earthen mounds could be found in the city around 1200 AD, and between 70 and 80 have been preserved. Many served as elevated foundations for governmental buildings, public courtyards or marketplaces, temples, and residential structures that belonged to the wealthy. Other mounds were used as burial pits, and some may have been built simply for aesthetic purposes, or possibly to honor certain deities.  

The largest of the Mississippian mounds of Cahokia can be found in the city’s 40-acre (16-hectare) central plaza, which was the administrative hub of the city. This huge earthen structure, which covered 14 acres (six hectares) and rose 100 feet (30 meters) off the ground, is known as the Monks Mound.  

Built in two levels and shaped like a four-sided pyramid, Monks Mound is the largest earthen structure found anywhere in the Western Hemisphere, and it is the highest of all the Cahokia Mounds. It is believed that the Mississippian equivalent of the city hall would have stood on top of Monks Mound. This building (and any structures built on its lower level) would have been accessible by a long stone staircase. 

Up to now, only a fraction of the land space in Cahokia and around the Cahokia Mounds has been excavated. As the new discoveries of the team of researchers from Saint Louis University shows, there are still copious quantities of ruins and artifacts waiting to be excavated in the spaces between and around the city’s mounds, which are the primary visible reminders of Cahokia’s existence. 

An aerial view of Monks Mound, largest of the Mississippian mounds of Cahokia. (Public domain) 

The Cahokia Mounds and the rest of the city are all included in the Cahokia Mounds State Historical Site, which was designated a UNESCO World Heritage site in 1982. During the latest excavations, the Saint University archaeologists and their students went to extraordinary lengths to ensure that they did no damage to this culturally significant location. “I’m not interested in destroying features, just documenting them,” said Mary Vermilion, an associate professor of anthropology and archaeology from Saint Louis University who supervised the dig. 

Because they disappeared in the 14th century, or roughly 100 years before Columbus arrived in the Americas, little is known about the Cahokian version of the Mississippian culture. The people were likely assimilated into neighboring Native American cultures after experiencing a cultural decline in the 1300s. Over time the memory of their origins was lost. 

Ongoing excavations at Cahokia should reveal a lot of fascinating information about how the Mississippian people worked and lived on a daily basis, as will a series of aerial surveys of the city and its surrounding region that will be carried out using LiDAR (light detection and ranging) remote sensing technology. The latter project, a joint initiative of Saint Louis University and the US National Geospatial-Intelligence Agency, will attempt to locate any hidden mounds or buried structures that might be located in swampy and forest-covered areas near the periphery of the ancient city.    

Top image: View of Cahokia Mounds State Historic Site. Source:  Zack Frank / Adobe Stock