PRR is the Panhandle and NYC is the MC Joliet Cutoff. They cross a little further to the west at the Hartsdale Junction. The NYC track in the upper-left corner is the NS/NYC/Big4/Egyptian route. It was called the "Danville Secondary" by the railroad crews. [post comments] MC and EJ&E ran parallel to each other through here with MC northish of EJ&E. The yard on the left of this diagram is a joint PRR+EJ&E Yard. The EJ&E Griffith Yard has actually expanded.
(Update: Pennsy also had a "Hartsdale Yard" in this area.)
ejearchive has a detailed map of the Hartsdale-Griffith area. I found it in a 1965 USS Detail Rail Maps section under Maps link at the top.
This yard was used to help interchange cars between NYC's Elkahart-Kankakee trains (k a e l and e l k a) and the Hartsdale Local. The local would serve the Ford Plant at Chicago Heights and "Kellogs at Munster on the Hartsdale siding. The Hartsdale local would come up the Wye Hill, pick them up. and deliver them then set out the empties." "These cars were on time delivery." [various Phil Boldman comments on a post]
Not only is the Hartsdale Yard gone, the main track has been torn up in places. Why not tear up all of the track since...