The Baltimore and Philadelphia Railroad was a railroad line built by the Baltimore and Ohio Railroad (B&O) from Philadelphia, Pennsylvania, to the Maryland-Delaware state line, where it connected with the B&O's Philadelphia Branch to reach Baltimore, Maryland. It was built in the 1880s after the B&O lost access to its previous route to Philadelphia, the Philadelphia, Wilmington and Baltimore Railroad (PW&B). The cost of building the new route, especially the Howard Street Tunnel on the connecting Baltimore Belt Line, led to the B&O's first bankruptcy. Today, the line is used by CSX Transportation for freight trains.
