Before CSX Transportation operated trains on the Saginaw Subdivision, it was originally owned by the Pere Marquette Railway. In the year 1947, the PM was acquired by the Chesapeake and Ohio Railway. It continued under the control of the C&O until 1973 upon which the Chessie System assumed operations of the line. In 1980, when the Chessie System merged with the Seaboard System Railroad, the line became owned by its current owner, CSX. Over the years the line has lost a lot of traffic and many of the industrial spurs have since been abandoned. The Flint and Holly Railroad was built by businessman, and later Michigan Governor, Henry H. Crapo in the 1860s to serve his lumber mill. A park near the junction of Canadian National Railway's Holly Subdivision, is named for him and a Michigan Historical Marker about him and the railroad's section stands there.
Toledo to Plymouth
The line begins in Toledo, Ohio, where it connects with the Toledo Terminal Division. Heading north, the line comes into the village of Carleton, Michigan. In Carleton, the Conrail Lincoln Secondary branches off and the Canadian National Railway's Flat Rock Subdivision crosses. Continuing onto Wayne, Michigan, the line crosses the Michigan Line, operated by Amtrak. CSX trains can interchange with NS here. There is a Ford automobile plant, which requires autorack cars for loading. North of Wayne, it enters Plymouth, Michigan. At Plymouth Diamond, the Saginaw Subdivision meets the east-west CSX Plymouth Subdivision-Detroit Subdivision line.
Beyond Plymouth the line crosses the now abandoned Michigan Air Line Railroad in Wixom. Then the line continues north. North of Plymouth is the village of Holly, where the line crosses CN's Holly Subdivision near a historic abandoned depot. In Flint, it interchanges with Canadian National's Flint Subdivision at the Atwood Wye. Also in Flint is the McGrew Yard and engine facilities for CSX equipment. In Genesee County, it closely parallels M-54 for several miles. Lake State Railway began leasing the line from Plymouth to Mount Morris starting in early March 2019.
Mount Morris to Saginaw
On October 29, 2005, Saginaw Bay Southern Railway began leasing over 67 miles of CSX Transportation trackage, part of which includes the Saginaw Subdivision from Mount Morris to Saginaw.
Traffic
As with most lines in the Detroit, Michigan, metropolitan area, automobiles are the main source of revenue on the Saginaw Subdivision, although other freight is important for the businesses too. Once a month, a BNSF Railway contracted Powder River Basincoal train works its way up the line. Plus, local freights diverging onto or off the Lincoln Secondary use the Saginaw Sub to head to or from Toledo.
Passenger service
As of 2019, there is no passenger service on the Saginaw Subdivision.
Pop culture
In the computer game seriesTrainz, the Saginaw Subdivision is available as a user-created route on the Trainz Download Station. In Trainz 2010, it is available as a built-in route.
