chrism:
The tracks you refer to are part of the former Milwaukee Road Dunning Line which went to the Chicago State Hospital north of Irving Park Rd. The line started at a connection with the Milwaukee Road\'s West Line across from the Mars plant, west of Narragansett.
This hospital complex went by various names over the years including Chicago-Read.
Trains delivered coal to its powerplant along with food and other goods. There were a number of other customers along the Dunning Line-including the brickyard-not the shopping center named after it, but the actual brickyard and clay pit-but as customers faded away, converted to truck delivery, etc., the Dunning Line was gradually cut back. In 1969 it was severed at Roscoe to service Kimbell Candy, then in the early 1980s at Diversey.
The last customer the Dunning Line was/is Chicago Steel & Die just south of Diversey. A tail track was left in place to the north of Diversey for trains to back down the spur.
My book \"The Milwaukee Road in Chicago\" includes a chapter on the Dunning Line with maps and photos if you would like more information.