When I was still working for CSX - one night 'surfing the company web' I came across several files that denoted all the mergers and acquisitions of the carriers that were involved in creating the Chessie side of CSX. Another file contained the lineage of all the carriers that came together to form the Seaboard side of CSX. As I recollect there were well over 600 individually named 'railroads' that were involved in these 'deals'. The reality is that while most were real tie, rail & locomotive company's, there were a number of paper only organizations that were created for financial reasons only and they never got beyond existing on paper.
In the mid-1980s, one of my employer's attorneys came across an old file with the SAL's lineage and sent it to my supervisor and I. Through the Seaboard System, SAL lines served all four of our major manufacturing sites, some with reciprocal switching agreements, so the document was somehow important in laying out terms and conditions of rail service. I wish to heck I'd made a copy of it, but somehow failed to do that. As you wrote, the details were dizzying, with dozens of mysterious railroads lost to history. The SAL was a latecomer, stitched together from dozens of roads, themselves products of earlier combinations.
