Where is Cahokia the largest urban center in U.S. territory prior to Philadelphia in the 1800s?

Cahokia, located near present-day St. Louis, Missouri, was the largest urban center in the U.S. territory before Philadelphia during the pre-Columbian era, particularly around 1050 to 1200 CE. It was part of the Mississippian culture and featured large earthen mounds, a complex society, and extensive trade networks. At its peak, Cahokia had a population that may have reached tens of thousands, making it a significant hub of activity and culture in North America long before European colonization.