The biggest industry between Hillsdale and Ypsilanti would have been the cement plant at Cement City....other than that, I would guess that it was mostly small grain elevators, lumber yards, coal and fuel oil distributers and some gravel pits in the Somerset area. In Hillsdale proper, there was a large manufacturing factory located along this line on the east side of the city that may have sent some stuff east to Detroit using this line (especially during the WW 2 years), but I have no proof of that; most of the traffic out of Hillsdale was sent east to Toledo using the Old Road.