The South Pennsylvania Railroad is the name given to two proposed but never completed Pennsylvania railroads in the nineteenth-century. Parts of the right of way for the second South Pennsylvania Railroad were reused for the Pennsylvania Turnpike.
The first South Pennsylvania Railroad was originally chartered as the Duncannon, Landisburg and Broad Top Railroad on May 5, 1854. Its intended route began in Duncannon, passed through Landisburg and Burnt Cabins, and ended on the Juniata River via the Broad Top Mountain coalfields. On May 5, 1855, it was renamed the Shermans Valley and Broad Top Railroad, and the planned northern terminus changed to the mouth of Fishing Creek, in Perry County near Marysville. An amendment to the charter on May 12, 1857 allowed it to connect with the Allegheny Portage Railroad and the Pittsburgh and Connellsville Railroad. Around this time, two miles of the proposed route were in fact graded. On March 31, 1859, it was given the grandiose name of Pennsylvania Pacific Railway, with the rights to extend into Maryland and Virginia. On April 1, 1863, it was renamed as the South Pennsylvania Railroad. Despite feverish promotion, including plans for 200 miles (322 km) of line from Marysville to West Newton (on the Youghiogheny River), no further work was completed. The two miles (3 km) of grading were sold off in 1872 and the charter became dormant on May 31, 1879.
The unused charter of the defunct South Pennsylvania Railroad was revived in the 1880s as a weapon in a growing war between the New York Central Railroad and the Pennsylvania Railroad, the two major Eastern railroad systems. William H. Vanderbilt, who controlled the New York Central, learned that the Pennsylvania had obtained control of the New York, West Shore and Buffalo Railway, a newly built railroad whose line paralleled the route of the New York Central between New York City and Buffalo. Vanderbilt viewed the West Shore project as a Pennsylvania Railroad incursion into prime New York Central territory and a threat to the Central's supremacy in the area.