The Chicago transfers were quite intricate. All of the routes shown were also used for transferring mail and express cars, and shuffling around Pullman cars between assignments, so the end of transcon service didn’t end the transfers. Here are some paths:
PRR to C&NW(UP/SP): East side Union station through tracks to Panhandle via Western Ave. to C&NW California Ave coach yard.
PRR to MILW (after 1955): East side Union station through tracks to Western Ave.
PRR to AT&SF: South through 21st st, reverse east to AT&SF Archer Ave yard
PRR to CB&Q: same station, same side.
NYC to C&NW: St Charles Air Line west from 16th St. to C&NW Rockwell sub, north to California Ave. Alternate route via Union Tower and east side Union Station bypass tracks. The westbound cars off the Wolverine were on the only MC train using LaSalle at the time. If other MC trains had been involved, the route would add the IC Iowa line from Central to 16th St.
NYC to MILW: Air line, Union tower, Union Station route to Western Ave.
NYC to AT&SF: This is a little complicated by the track arrangment at 16th St. Either SCAL to Union tower, back around Union Station Wye to 21st St, then Archer Ave, or wye/backup move onto SCAL, back through 16th St. onto IC Iowa Line, then to AT&SF Archer Ave.
NYC to CB&Q: SCAL, Union tower
B&O to AT&SF: Grand Central over B&OCT bridge, back up on SCAL to 16th St. IC Iowa Line to AT&SF Archer Ave.
I don’t recall the B&O doing anything with the UP, but that would probably have gone B&OCT west to C&NW Rockwell sub. If it ever existed it was gone pre-MILW “City” trains.
B&OCT used boiler RS1s, AT&SF used boiler RS1s and H1244TSs, NYC used RS1s, RS2s, And BLH 1200 HP switchers(later reengined by EMD). C&NW and MILW used boiler RS2/3s (some of C&NWs were “Hammerhead”). PRR used