 Havana Hopewell sites have been found in Illinois, northwest Indiana, southwest Michigan, southern Wisconsin, and Minnesota and northeast Iowa.Hopewell trading networks were quite extensive, with obsidian from the Yellowstone area, copper from Lake Superior, and shells from the Gulf Coast.The Toolesboro Mound Group in Louisa County, Iowa included a large octagonal earthen enclosure that covered several acres; earthworks of this style are reminiscent of the monumental construction seen in Chillicothe and Newark, Ohio.