I went to school up at Michigan Tech, and had a professor that studied industrial archaeology specifically in the UP, because the people in the Keweenaw had unique access to float copper (pure copper that can be mined directly from the ground). He said their ability to produce metal tools gave them a lot of economic power, and that they traded that with neighbors.

I wonder if having access to those tools is one of the reasons such a large scale operation was feasible so far north