Huntington, WV area customer 1949 and 1950 car counts – a month by month breakdown of cars shipped and received for Huntington area customers
B&O Ohio River Railroad 1981 Waybills – a large collection of waybills mostly from 1981 for inbound shipments to Ohio River Railroad customers
B&O St. Louis Division Customers 7-1-1973 – a great overview of the St. Louis Division including customers, commodities shipped, and the jobs serving them.
B&O Baltimore Deliveries 5-27-1901 – a listing of many Baltimore area industries in 1901 and which yard carloads should be routed to reach them
Multimodalways.org hosts Freight Working Book 57 from 1957. They also have Block and Station Record of Train Movements from CGW Jct. (Chicago) and Keyser, WV.
Historic Railroad Documents has a 1923 freight schedule, employee timetables, and lineups from Willard Tower from 1969.
The Baltimore and Ohio Railroad Historical Society offers a huge selection of freight classification books and other resources.