Following the merger, the Ma and Pa operated through passenger and freight trains between York and Baltimore, as well as local trains at each end of the line, hauling mail and express, slate, marble, anthracite coal, lumber, furniture, and agricultural products to market. Particularly on the Pennsylvania Division (Delta–York), slate from Delta and manufactured goods from Red Lion and York were mainstays of the railroad's outbound freight traffic in the early years. On the Maryland Division, inbound anthracite coal deliveries accounted for a significant volume of carloadings, along with milk from the many dairy farms in the area. One early morning train from Fallston boarded more than 1,100 gallons of milk daily and was dubbed the "Milky Way". The line was profitable and traffic volume was such that additional locomotives were necessary. The Ma and Pa acquired two 0-6-0 Baldwin switchers in 1913, #29 and #30 "(pictured)", called "jewels of engines, in some respects the most attractive the road had", by writer George Hilton in "The Ma & Pa – A History of the Maryland & Pennsylvania Railroad". The next year, three 2-8-0 "Consolidations" by Baldwin were added to the roster, providing more powerful locomotives for the Baltimore–York through freights. At its peak, the railroad had 16 locomotives and 160 pieces of rolling stock, with 573 employees.