Historically, Atlantic Coast Line had partnered with Florida East Coast, for passenger service continuing south of Jacksonville to Miami. But in 1963, four years before the merger, Florida East Coast was impacted by a lengthly strike. Atlantic Coast Line needed to connect with its then rival Seaboard, for access into Miami. Atlantic Coast Line had its own route to Tampa, which crossed the Seaboard route at Auburndale. A connecting track exists at the east quadrant. In addition, the McDonald Connecting Track at the south quadrant enables trains to travel between Tampa and Miami.
In 1970, three years after the merger, Seaboard Coast Line achieved consolidation of all passenger traffic between Richmond and Petersburg onto the former Atlantic Coast Line route. South of Petersburg, the Southwest Lead connected between the two former railroads.
In 1986, Seaboard Coast Line successor CSX downgraded the former Seaboard line between Petersburg and Raleigh. For Amtrak to serve Raleigh and points south along the former Seaboard line, trains would connect between the former Atlantic Coast Line the former Southern Railway at Selma with a connecting track at the north quadrant. The Southern Railway line extended west of Selma to Raleigh. A connection was already in place at Raleigh, as Southern had trackage rights over Seaboard between Raleigh and Fetner.