Cool post, we're almost in my backyard. I'm about ten blocks due north, and I used to be about five blocks due east. I love this area.
The line originally came from the far west (think junction between West and North lines), ducked under the expressway, crossed CNW, then crossed the river, and served the mini-mill and scrapyard. As the neighborhood started gentrifying in the 1970s and industry evaporated rapidly, there is only the two industries left across the river. UP delivers cars to a shortline that then crosses the river and uses mostly street trackage to switch Finkl and General Iron.
There was once a track that went north on Lakewood to a chocolate factory up by my house, but it's all quite nice city houses now. The track remains in Lakewood, though. There was also once a track that went all the way downtown on Kingsbury.
CP sold this operation about five years ago. This site is really good and will tell you all you want to know: http://chicagoswitching.com/v6/
Some other good shots:
http://www.railpictures.net/viewphoto.p ... 319&nseq=7
http://www.railpictures.net/viewphoto.p ... 785&nseq=1
http://www.railpictures.net/viewphoto.p ... 458&nseq=5