Perhaps a map or two can help clarify some distinctions between
the ASL, WB&A, B&A, and B&O, all of which met near the Baltimore
City / County border.
The 1953 aerial above illustrates the ASL 1 (original) vs ASL 2 (later)
With the arrival of Patapsco Avenue around 1960, the B&A which had been
operating along the ASL 2 alignment switched back to ASL 1 where a
bridge was added for grade separation from the then-new Patapsco Avenue.
Patapsco Avenue runs within the city, just inside the city line. As of
2018 only utility lines -- and railfans -- still follow the ASL 2 alignment.