By the s a significant decline in railroad passenger traffic had caused a subsequent decline in the use of railway train crews for transporting and processing mail To fill the void the postal service began using highway buses instead on some routes This is the first Highway Post Office bus which began service on February Manufactured by White Motor Company of Cleveland OH the bus operated between Washington DC and Harrisonburg Virginia Although the bus in the Postal Museums collection was decommissioned in the s the Highway Post Office service ran until June