Railroads. Freight and passenger train service unit costs (selected expense accounts) of class 1 steam roads in United States, including proportion of mixed-train and special-train service (compiled from 164 reports representing 180 steam roads, switching and terminal companies not included), Apr. 1922 and 1921. and 4 months [ended with Apr.] 1922 and 1921; [prepared in] Bureau of Statistics.