In fact it was at one time. During the Bronze age they mined the copper of Lake Superior. Specifically the mines of Isle Royal. This has recently been proven by the find of a sunken Phoenician ship laden with copper ingots the shape of hides within the Meditranian basin that have the same copper purity content as the copper of Lake Superior. Pure copper can be traced to it’s origin in this way. There is no doubt but that the copper in that Phoenician ship came from Lake Superior.