Jan Bartek – AncientPages.com – Cahokia emerged as the largest city north of modern-day Mexico around 1050 CE, with a population exceeding 20,000. It was composed of three connected precincts located in the central areas of the northern “American Bottom,” a floodplain along the Mississippi River within what is known as “Greater Cahokia.”
Artist’s conception of the Mississippian culture, Cahokia Mounds Site in Illinois. The illustration shows the large Monks Mound at the center of the site with the Grand Plaza to its south.
Credit: Herb Roe – CC BY-SA 4.0 – Left: Illustration of the location of the 14C samples in the Mitchell Log ring sequence. Credit: Kessler et al. 2025
By 1100 CE, Cahokia had become the primary political and administrative hub in the Mississippian midcontinent and Southeast. However, its population and influence began to wane before 1200 CE. The causes for this decline remain uncertain, with theories suggesting climate change, resource depletion, environmental disasters, and socio-political fragmentation.
Archaeological research has extensively focused on reconstructing population dynamics and environmental trends in the American Bottom. Equally important is understanding when significant religious and political changes occurred in and around Cahokia. At its zenith, Cahokia’s political power was linked to acquiring exotic goods and regularly constructing monuments. Analyzing when these exotic materials were imported and how monumental construction evolved can shed light on Cahokia’s peak period of political integration and interregional influence.
A typical form of monumental construction at Mississippian sites involved marker posts—large wooden structures made from tree trunks set vertically near key buildings or atop pyramidal mounds within community spaces like courtyards or plazas. Poles and posts are frequently mentioned in historical and ethnographic records concerning Indigenous peoples and their practices across the Americas. These poles often held significant power or sacred status, and some cultures regarded them as persons or ancestors.
Poles played a central role in various ceremonies and festivals, which could involve activities such as dancing around them, making offerings to them, climbing them, or even performing acrobatic feats by attaching oneself to the pole.
These massive poles were occasionally relocated to possibly mark a precinct’s axis mundi, represent a spirit being, or serve as focal points for rituals involving pole-climbing or pole-flying activities.
Cahokia Mounds – Reconstruction. Credit: Thank You (24 Millions ) views – CC BY 2.0
The Cahokians are recognized for their impressive construction of massive marker posts, most notably the Mitchell Log, which has recently been studied by researchers. This log is a 3.5-meter-long basal remnant of an upright marker post, found in 1961 at the site’s central plaza. It was left in a ramp within a 4-meter-deep post pit after breaking during extraction. When dry, this portion weighed just over one metric ton. Considering the depth of the pit and length of the extraction ramp, it is estimated that the original marker post stood at least 18 meters tall and may have weighed between four and five metric tons.
These wooden marker posts serve as valuable monuments and artifacts for dating purposes, offering insights into the scale and nature of Cahokia’s urban development. The origin and cutting date of the Mitchell Log indicate that Cahokian networks reached far south during their Stirling-phase peak, highlighting their extensive influence during this period.
The pole, crafted from bald cypress, was not native to the Greater Cahokian area and thus had to be imported. Radiocarbon dating indicates that the tree was likely cut down around 1124 CE, at which point it was approximately 194 years old. Strontium isotope analysis suggests that the bald cypress originated from regions such as southern Missouri, northern Arkansas, western Tennessee, or southern Illinois. The closest of these sources is at least 180 km away.
The method of transporting the Mitchell Log remains uncertain. Scientists propose that floating or rafting logs upriver through Mississippi’s sloughs and backwaters would have been a logical approach. Alternatively, overland transport via trails and roads connecting Cahokia to nearby communities might have been used—a method similar to that at Chaco Canyon, where logs were moved up to 70–80 km for construction.
Location of the Mitchell Log within the site and within Great Cahokia (panel A). Base map is from the “sptools” library in R. Aerial photograph is archival imagery from the Illinois State Geological Survey—illustration of the location of the 14C samples in the Mitchell Log ring sequence (panel B). Credit: Kessler et al. 2025
The acquisition of the Mitchell Log coincides with a period when monumental construction in earthen and wooden forms reached its peak in Cahokia. This era also saw highly integrated regional agricultural systems and an influx of exotic materials in the area. Therefore, this log provides a near-direct date for when Cahokia experienced its political and economic zenith.
Assuming the log stood for one or two generations before natural decay set in—leading either to its collapse or removal—it would have remained until about 1150-1175 CE. This period aligns with indirect dating evidence from nearby ceremonial buildings that were abandoned as significant changes occurred at the Mitchell site. Consequently, this log may offer valuable insights into the timing of Cahokia’s decline.
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Further research is needed to determine whether other marker posts were removed or broken during this time frame.
“In essence, marker posts of non-local wood types joined other exotic items as symbols of power and authority in Cahokian society. The dating of the Mitchell Log provides one historical datum of this process,” the researchers write in their study.
The study was published in the journal PLOS One
Written by Jan Bartek – AncientPages.com Staff Writer