Thanks, Ray. From the link it looks like there is still some uncertainty as to whether the CTA still has a physical link to the outside railroad world. The Skokie connection that is referenced was in place as late as 1988 but gone by the early 1990s. It came off the C&NW Weber Line just south of McCormick Blvd and connected to the CTA shops. At one time that connection from the C&NW was used to service former North Shore Line industries just north of Oakton that were marooned after the NSL went out of business in 1963.
The CTA connection to the Milwaukee Road was severed in 1973 when the Milwaukee Road cut back service to Racine Avenue on the C&E.