 Founded on what is often referred to as the "Nile of North America," the region surrounding the confluence of the Mississippi and the Illinois rivers, the Center for American Archeology specializes in North American pre-Columbian cultures of the area.Due to successive settlement along the rivers, the area is particularly rich in Woodland Period artifacts, especially those of the Middle Woodland Hopewell culture, and later Mississippian culture.The Center has been associated with years of excavation at the Koster Site in Greene County, Illinois.