Tunnel City is an unincorporated census-designated place in the town of Greenfield, in Monroe County, Wisconsin, United States, named after the train tunnel just to the west which was used by the Chicago and North Western Railway (track now abandoned west of the tunnel) and the Chicago, Milwaukee, St. Paul & Pacific Railroad (Milwaukee Road). The existing track is owned by the Canadian Pacific Railway, and carries the Amtrak Empire Builder passenger train, though rail traffic is dominated by freight. As of the 2010 census, its population is 106. Tunnel City has an area of 0.310 square miles (0.80 km2), all of it land.
Coordinates: 44°00′26″N 90°33′56″W / 44.00722°N 90.56556°W