The Maryland and Pennsylvania Railroad, colloquially 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 main line took 77.2 miles (124 km) to connect Baltimore and York, although the two cities are only 45 miles (72 km) apart.

The town of Bel Air is the county seat of Harford County, Maryland. According to the 2020 United States census, the population of the town was 10,661.