Where in Richmond VA do ACL passenger trains interchange with the C&O for passenger trains going to Chicago.
No shared station. C&O shared Main St with SAL, ACL used Broad St. RF&P trains used the connecting road’s (ACL’s or SAL’s) station, with RF&P-only trains using Broad St. SAL started using Broad St in the late 1950s, with their trains still passing Main St. on the viaduct there.
There was a “Broad and Main” streetcar (and I presume the replacement bus still runs) that connected the two stations, but I suppose most used a taxi.
Broad Street is now a museum, with Staples Mills Road station serving Richmond. After a few years of being shuttered, Main St was reopened for Newport News trains in the 2000s. Long term plans involve re-opening the “S-Line” (former SAL) for passenger trains to Petersburg, Norfolk and the Carolinas and Florida, which would serve Main Street again. The basic EIS has been completed but the work is still a long way off, if it ever starts.