Duplainville, WI
Whilst once in Wisconsin on business, and shortly before the drive to the airport, a little free time was available so I asked colleagues where the best place was to observe trains before I hit the road. Duplainville was the answer. Two lines cross over each other here. North to south the Canadian National operates what was the former Wisconsin Central (SOO Line) between Fond du Lac and Chicago. East to West the Canadian Pacific Railway has the former Milwaukee Road route between Twin Cities and Chicago. It has the potential to be quite busy here, although on my first, albeit very short, visit, only two trains were seen, both on the CN. But it will be a place I'll look out in the future, should the opportunity arise.