In addition to the mainline that joined Illinois Central to access Chicago, they built the "Joliet cutoff" that went from Indiana to Joliet.
|Peter Dudley posted|
A map excerpt, retrieved from Joseph Tuch Santucci's copy of the September 1945 Michigan Central Railroad Employee Timetable, shows M.C.R.R.'s Michigan Line mainline, between Marshall MI and Chicago IL.
The M.C.R.R. - owned mainline actually ended at Kensington IL. Access to Chicago's Central Station was via a trackage-rights agreement with Illinois Central Railroad (IC), in force since M.C.R.R.'s 1852 arrival in Chicago. M.C.R.R.'s parent, New York Central System (NYC), moved its remaining trains at Central Station to NYC's LaSalle Street Station in 1956.
Note that a segment of M.C.R.R.'s Air Line Branch (right), between Niles and Three Rivers, had already been abandoned by 1945. Through freight trains had previously used the relatively-underpopulated, former - Michigan Air Line Railroad (MAL) diagonal route as a shortcut.
I believe M.C.R.R.'s Joliet Branch enabled western through shippers to avoid congestion at Chicago, in much the same way that the "Niagara Falls Route" provided a fast freight route to New England, avoiding Buffalo.
Today's westbound Amtrak WOLVERINE passenger trains follow the former M.C.R.R. mainline as far as Porter IN, the west end of the Amtrak-owned Porter / Kalamazoo 110-mph territory. West of the junction with the former - NYC east / west mainline at Porter, the WOLVERINE follows Norfolk Southern Railway (NS) track to Chicago's Union Station. This segment is often slow, but Amtrak and the State of Indiana are working on it.
This map excerpt was originally posted in Michigan Central Railroad Group (https://www.facebook.com/groups/NiagaraFallsRoute1/) on September 20, 2014.