This line started out as the Chicago North Shore and Milwaukee Railroad, an interurban line that connected Chicago with Milwaukee, WI. Between Chicago and Northbrook, it ran parallel and adjacent to a Chicago and North Western Railroad mainline, 50 feet to the west. However, the CNW's mainline was ill-maintained and was increasingly seeing derailments and other accidents. So when the North Shore line fell to bankruptcy in the early 1960s, the CNW saw fit to relocate their mainline to that of the well-maintained North Shore line, since relocating was much cheaper than rehabilitating their own line, despite their mainline being considered a "bypass" to their second mainline, to which this line connected at Northbrook.
Freight traffic along the line declined over the years, until the line was downgraded to local use, serving a couple of local businesses, including a lumber yard and gravel company for a couple of years. The CNW finally ceased traffic along the line in 1995, and the Union Pacific (which merged CNW in 1995) filed for abandonment of the line in 2001, with the most of the track removed in 2004-05. Some track and a railroad trestle in Northfield remain, and all of the grade crossings are paved over. Consideration has been given to rebuilding this ROW in the future as an extension of the Chicago Transit Authority's "Yellow Line".
The line ran north from Lincolnwood (just north of Chicago), through Skokie, Glenview, Northfield, Glencoe, and ended in Northbrook with a connection with the other CNW mainline, which is now in heavy use by Union Pacific.
Thanks to Greg J for contributing information about this route.