If one were to explore the neighborhood just north of Callowhill Street between 20th and Broad Street, the casual observer might be perplexed by what appears to be a sunken urban greenway running parallel to Callowhill Street. This trench, some 40 feet wide and 20 feet deep, is now overgrown with trees and littered with trash. While it is hard to imagine, this was once a busy railroad thoroughfare belonging to the Philadelphia & Reading Railroad. The origins of this portion of the railroad date back more than a century and represented an important route for the Reading to deliver goods into Center City. In the mid 1800’s, the Reading, whose main terminal was at Port Richmond, was looking for access to the heart of Philadelphia. Its chance came in 1850, when it bought the old Philadelphia and Columbia line between Peter’s Island in the Schuylkill (Belmont) and Broad and Vine Streets.1
By 1893 the volume of railroad traffic along this line, which the Reading referred to as its City Branch,1 had become so great that the city fathers felt it necessary to intervene.2 At this time, all the railroad trackage was at street level, which meant numerous grade crossings as the railroad traversed the grid of Philadelphia streets. A nice example is at Broad and Noble Streets, where at least three tracks crossed the intersection, complete with crossing gates and watchman’s shanty. In addition to the traffic problems this arrangement created, the city fathers were sensitive to the fact that as the railroad traveled south along the east bank of the Schuylkill River, it ran right in front of the entrance to Fairmount Park, a less than pleasing spectacle. As part of an agreement to allow the Reading to build its new passenger terminal at 12th and Market Street, the railroad was also required to find some solution to the problem of street trackage.2
After numerous plans it was finally decided that the tracks would be placed below street level, an interesting departure from the usual railroad strategy. Both the Reading Railroad and its rival, the Pennsylvania Railroad, typically opted for grade elevation rather than lowering the track, a prime example being the Pennsylvania Railroad’s elevated trackage into Broad Street Station, later nicknamed the “Chinese Wall”. The project would consist of two major parts. The first was along Pennsylvania Avenue from Taney Street east to 21st and Hamilton. Four tracks would be placed in a tunnel running underneath Pennsylvania Avenue. The second part was an open subway from 21st Street to 13th and Callowhill.2
Work began in 1897 and the magnitude of it cannot be overstated. There was an enormous amount of earth to be excavated. In addition, there was the logistical nightmare of doing construction without disrupting service to various industries along the line, so temporary track needed to be laid. Since the track was going below street level, various sewer lines had to be rerouted, and bridges needed to be constructed to keep through streets open. Even the railroad’s own engine servicing facilities would be demolished so that the tracks could be lowered.
Despite the immense scope of the project, much of the work was completed within two to three years. By 1900 the line was fully functional and connected to the Reading Passenger Terminal at its eastern terminus. The line remained active for nearly 100 years. In 1984, the Reading Terminal closed, and by 1997, the last remaining freight customer along the line closed, marking the end of rail service.3 While little remains today of what was once a key industrial section of Philadelphia, we will look in Part II at a number of places along the line during construction and see the importance of the railroad and the industries it served.
 Pennsylvania Railroad Company. “Inspection of Physical Property by Board of Directors, November 10-11-12, 1948.” http://www.railsandtrails.com/PRR/BOD1948/history.html
 Webster, George S. and Wagner, Samuel T. “History of the Pensylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith.” Transactions of the American Society of Civil Engineers, v. XLIV (Dec. 1900), pp. 1–33.
 Castelli, Douglas, Hill, Erin, Johnson, Michael & Jones, Dayle. “Innovative Rail Technologies Cross-Town Rail Line: Final Report.” Appendix B. (2003) http://hdl.handle.net/1860/116