Im not surprised, just a bit north of there the Keeweenaw Peninsula in Michigan has the largest deposit of native copper in the world and would have been fairly prosperous in that era trading copper and copper objects across the midwest and beyond among natives. You can literally dig solid copper nuggets out of the ground there. Just busting up random rocks from the area will show you bright shiny copper bits inside. Any area nearby would itself gain a lot of prosperity from the trade and have decent populations which incentivizes a lot of native farming to feed everyone.