The city of Cahokia was the preeminent metropolis in its region in the year 1200, equal to the size of any European city at the time and the centre of a wide area of political, social and economic influence. Where was it, however?
Answer: Missouri, in the United States. It was near the modern site of St. Louis and a key centre of Native American culture.
Source: Cahokia – Domination and Ideology in the Mississippian World by Timothy R. Pauketat