The Maryland and Pennsylvania Railroad , familiarly known as the "Ma and Pa", was an American short-line railroad between York and Hanover, Pennsylvania, formerly operating passenger and freight trains on its original line between York and Baltimore, Maryland, from 1901 until the 1950s. The Ma and Pa was popular with railfans in the 1930s and 1940s for its antique equipment and curving, picturesque right-of-way through the hills of rural Maryland and Pennsylvania. Reflecting its origin as the unintended product of the merger of two 19th-century narrow gauge railways, the meandering Ma and Pa line took to connect Baltimore and York, although the two cities are only apart in a straight line.