However, in the end it was the cold front itself that generated squall lines.
They started out very thin and rapidly moving NNE. That was their strong point.
As the squall line became thicker it also lost some of it's edge, as you can see on the report map above. The squall line got thicker around the Gary Indiana area.
There was extensive damage in the town of Merril, WI from a potential tornado.
Overall, Wisconsin was definitely the hotspot for storms.