Business and community leaders decided in September 1881 that a short line railroad connecting Catonsville to Baltimore City would help foster Catonsville's growth, and the Catonsville Short Line Rail Road Company was incorporated on February 25, 1882. Ground was broken on December 6, 1883, and the first revenue run from Catonsville took place on November 10, 1884. Operated by the Baltimore and Potomac Railroad under a 99-year lease, the line ran from Catonsville's business district along the Mellor Avenue corridor, through the grounds of Spring Grove Hospital, into the Paradise and Kenwood communities, past St. Charles College, into Loudon Park cemetery, and there connected with the Baltimore and Potomac main line for travel to Calvert Station in Baltimore City. The railroad was approximately 3.7 miles long and made seven trips per day to Baltimore City and back. It immediately benefited local businesses by hauling lumber for new home construction and delivering large quantities of coal to St. Charles College and Spring Grove State Hospital. After the new electrified Catonsville trolley line began operating in 1897, much of the line's passenger traffic was drawn away, and passenger service ended in 1898, though freight service continued on a flexible schedule. Revenue declined during the Great Depression, and the company went bankrupt; in October 1945 the railroad was sold and reincorporated as the Caton and Loudon Railway. During the 1960s and early 1970s, trucking took over much of the movement of goods to and from local businesses, and in 1970 the conversion of the Spring Grove State Hospital power plant from coal to oil cost the line one of its few remaining customers, making trips increasingly sporadic. Penn Central, successor to the Pennsylvania Railroad, petitioned to abandon the line because of few customers and mounting losses, and the last carload to Catonsville arrived in April 1972.