The Philadelphia & Reading Railroad Bridge carries Norfolk Southern rail lines across the Susquehanna River between Cumberland County, Pennsylvania and Harrisburg, Pennsylvania. Some of its concrete piers encase stone masonry piers from an earlier truss bridge on this site, completed in 1891 by the Philadelphia, Harrisburg and Pittsburgh Railroad, which was then acquired by the Philadelphia and Reading Railroad to connect its Harrisburg and Lurgan lines. The current structure was constructed from 1920 to 1924 by replacing the trusses with concrete arches one track at a time. The bridge has fifty-one concrete arches, three more than the nearby Rockville Bridge. History In Harrisburg, the first bridge over the Susquehanna was built at the beginning of the 19th century on the site of today's Market Street Bridge. This led over the river island City Island, which is today surrounded by six bridges, including two railway bridges, with only the Philadelphia and Reading Railroad Bridge is used. Their predecessor structure was built between 1890 and 1891 by the Philadelphia, Harrisburg and Pittsburgh Railroad (PH&P), an association of several smaller railway companies that Harrisburg associated with about 75 kilometers southwest Shippensburg. The PH&P was later acquired by the Philadelphia and Reading Railroad (P&R), which thus made the connection of their rail network to the Western Maryland Railway in the southwest and strengthened their position in the competition with the Pennsylvania Railroad (PRR). The PRR controlled until then all railway bridges over the Susquehanna in Pennsylvania below Selinsgrove, as well as the upstream Cumberland Valley Railroad Bridge and Rockville Bridge. In the immediate vicinity of the Philadelphia and Reading Railroad Bridge - upriver on the Lemoyne side - are some pillars of a never-completed railway bridge of the South Pennsylvania Railroad. Planned in the midst of a fierce power struggle between the then major railway companies, construction of that bridge was halted in 1885 in the wake of a compromise negotiated by the banker JP Morgan. The originally single-track P&R bridge consisted of 23 wrought-iron truss girders with a length of 45.5 meters each, whereby the pillars of sandstone had already been designed for a later twin-rail expansion. Since such an expansion never came about, the one-sided load on the pillars over time led to their damage. With the emergence of more powerful and heavier steam locomotives at the beginning of the 20th century, the maximum load capacity of the bridge was reached. The