Cahokia mound settlement

Timeline

1. c. 1050–1150Cahokia core mound group · IllinoisThe settlement reached the largest scale of prehistoric North America; Monks Mound stood over 30 meters high, and the Woodhenge solar calendar and over 120 platform mounds formed a ceremonial and administrative center, trading shells, copper, and obsidian with the lower Mississippi and the Great Lakes region.
2. 1161–1170Cahokia site · IllinoisDuring this period the settlement's population continued to decline and new mound construction ceased, but Monks Mound and surrounding ceremonial areas were still used by small communities; archaeology shows traces of late-period activity in some areas.
3. c. 1200–1350Cahokia · United StatesClimate change, resource depletion, and regional political reorganization led to the settlement's complete abandonment; the mounds gradually became covered by vegetation until 19th-century archaeological excavations revealed its status as North America's largest prehistoric city.