The Atglen and Susquehanna Branch was built from 1903 to 1906 by the Pennsylvania Railroad as the middle segment of its Low Grade Line, a through-freight route of about 140 miles from Morrisville Yard near Trenton, New Jersey, to the Enola Classification Yard west of Harrisburg. Its completion relieved freight bottlenecks approaching Philadelphia by separating heavy through-freight traffic from passenger service and local freight on the main line through Lancaster and by bypassing Philadelphia altogether. It was the Pennsylvania Railroad's largest construction project to that date, involving a nearly $20,000,000 investment and an estimated 22 million cubic yards of earth and rock, and it created an unequalled freight route linking western markets to the ports of Philadelphia, New York, and Baltimore. To maintain the low grades and gradual curves needed for through-freight operation, the line crossed southern Lancaster County on a determined course, raising an earthen road on the Chester Valley floor west from Parkesburg to Safe Harbor, cutting deep canyons through the hills of the Susquehanna River Valley, blasting the prehistoric east bank of the Susquehanna River within Manor Township into a level shelf, and spanning valleys, streams, and the shoed horse's dirt road with about 90 masonry and steel bridges and culverts. Dedicated for service in July 1906, it functioned for decades as a streamlined rail corridor that met fuel and food demands along the eastern seaboard. The Pennsylvania Railroad electrified the line in 1938, ending a century-long era of steam locomotion there, with hydroelectric power from the Susquehanna River at Safe Harbor Dam feeding its catenary system. The route handled the freight demands of World War II without major changes, but the national decline of rail service in the second half of the twentieth century eventually led to its end. Another freight route to Philadelphia gained favor in the decade before the final freight movement on December 19, 1988; the line was abandoned as an active railroad in 1989, its rails were removed in 1990, and much of the route later passed to individual municipalities. In August 2013, Manor Township opened the southern half of its section of the former branch as part of the regional Enola Low Grade Trail.