I’ve finished patching up overlake boundaries in New York, Pennsylvania, and Ohio. @BMACS001 and I have been conflicting with each other a bit, since New York’s border with New Jersey needed a lot of work too, but I think we’ve managed to get our changes in.
For the rest of the Great Lakes states, the overlake state boundaries will be pretty straightforward to map, but the overlake county boundaries will be more difficult. The current status of Michigan’s county boundaries is still a subject of debate: the Census Bureau publishes authoritative-looking boundaries that the OSM community finds suspicious. I’d be inclined to map those boundaries if I can find any scrap of legislation regarding them. It’s entirely possible that they’re just inferences from PLSS surveys that took place.
Edit: @leonne has already mapped most of southeastern Michigan’s counties into the lake, so we’ll just run with that. We’ll need to reconcile them with the Newberry-imported boundaries that stop at the shoreline.