All of St. Louis to Longview is former (1950s) MoPac, as well as Taylor to San Antonio (until you get into San Antonio itself; the former MoPac station was at a different location). Longview to Dallas is former Texas & Pacific (a part of the MoPac system for essentially all of the 20th century). Dallas to Fort Worth is either former Rock Island (mostly, now) or else former MoPac (Texas & Pacific), depending on the vagaries of dispatching that day. Fort Worth to Temple is former AT&SF. Temple to Taylor, as Bob Dylan correctly notes, was former Missouri-Kansas-Texas (Katy). Chicago to St. Louis was formerly The Alton Route/Baltimore & Ohio/Gulf, Mobile & Ohio, depending on exactly which years you're talking about.