This is the USGS map for Mackinaw City in 1976.  The former Pennsylvania Railroad enters from Petosky in the southwest.  The former New York Central enters from the southeast.  The railroad car ferry brings railroad cars from St. Ignace, across the Straits of Mackinaw.  Mackinaw City's Union Station, which served both the NYC and the PRR is noted on the map.  (It is now part of a shopping mall).  The NYC roundhouse is also shown in the photo.