A switcher locomotive, shunter locomotive, or shifter locomotive is a locomotive used for maneuvering railway vehicles over short distances. Switchers do not usually move trains over long distances, instead they typically assemble trains in order for another locomotive to take over. Switchers often operate in a railyard or make short transfer runs. They may serve as the primary motive power on short branch lines or switching and terminal railroads.

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.