The Pennsylvania General Assembly chartered the Philadelphia & Trenton Railroad on February 23, 1832, to build a line between Kensington, Pennsylvania, and the Trenton Bridge at Morrisville, Pennsylvania. On April 16, 1834, the Philadelphia & Trenton Railroad opened an eight-mile stretch between Morrisville and Bristol, using horses to pull trains. In 1836, the Camden & Amboy gained a controlling interest in the line. On June 30, 1871, the Pennsylvania Railroad leased the Philadelphia & Trenton and started operating the line on December 1, 1871. A portion of the line folded into what is today the Northeast Corridor.
The Philadelphia, Wilmington & Baltimore Railroad was created through the merger of four earlier railroads: the Philadelphia and Delaware County Rail-Road Company; the Baltimore and Port Deposit Rail Road Company; the Delaware and Maryland Rail Road Company; and the Wilmington and Susquehanna Rail Road Company. The new line formed a single road between Philadelphia and Baltimore. The Pennsylvania Railroad took control of the company in 1881 following a fight with the Baltimore & Ohio Railroad. In 1902, the Pennsylvania Railroad merged the Philadelphia, Wilmington and Baltimore and the Baltimore & Potomac railroads to create the Philadelphia, Baltimore & Washington Railroad.