It's pretty simple. Conrail had three presences in Chicago. 1. PRR Panhandle, which is heavily abandoned today; 2. PRR/NYC parallel mains into downtown and associated yards; 3. IHB (a one-time NYC>PC>CR subsidiary).
This line comes in from the far south, around Arcelor-Mittal's former ACME Riverdale mill. It then proceeds northwest across the river where track stops (abandoned), intersecting the Rock at 103rd, suburban branch at 91st, and the track starts up again just north of Dan Ryan woods. It then proceeds due north all the way to the ex-CNW Western Ave yard now used by Metra. From there, it once turned due east to CUS. Conrail obviously had no interest in using CUS, and didn't really have a heavy emphasis on the Panhandle anway.
PRR/NYC parallel mainlines to downtown:
Starting in Gary, the NYC line parallels the tollway while the PRR Fort Wayne line parallels the ex-Wabash. They converge just north of the Gary Airport and run parallel along the edge of the lake to the IL state line. They continue in parallel along the tollway to Englewood at 63rd and State. The PC rationalized the mains, alternating between the immediately adjacent former PRR and NYC between East Chicago and Englewood. North of Englewood, the NYC followed the Rock to LaSalle station, but Conrail had no use of that line. From Englewood, Conrail used the ex-PRR yard at 63rd/State for intermodal (NS still does) and the ran the ex-PRR due north and immediately to the west of the Dan Ryan to downtown.
There are a few yards on both the Fort Wayne line and Panhandle, but Conrail did most of their sorting in Elkhart and pre-blocked trains for western carriers there. Elkhart is a monstrous and busy operation.
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