Donuel, I got out my atlas and reviewed Lake Michigan geography. Four states share it.

If we pretend that the long, north-south loop of Lake Michigan is a zucchini, then Illinois and Indiana share the blossom end. Wisconsin and Michigan share the long sides, and Michigan's Upper Peninsula gets the stem end.

The DH pointed out that the image of Wisconsin (say) that we have in our minds is a map of the land, but the actual state line between Wisconsin and lower Michigan is in the middle of the lake.