The Pennsylvania Railroad, legal name The Pennsylvania Railroad Company, also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia. It was named for the commonwealth in which it was established. At its peak in 1882, the Pennsylvania Railroad was the largest railroad, the largest transportation enterprise, and the largest corporation in the world.

A reporting mark is a code used to identify owners or lessees of rolling stock and other equipment used on certain rail transport networks. The code typically reflects the name or identifying number of the owner, lessee, or operator of the equipment.