In late 1946 / early 1947 Canadian Pacific built in their home shops a single covered hopper numbered 38000. Unlike most covered hoppers of the era, the side bracing ribs were installed inside the car, resulting in the flat 'slab side' appearance.

 

In 1948 they placed the first of several orders with the National Steel Car company for 200 covered hoppers of similar design. This was the first of many orders from several car builders for Canadian 'slab side' covered hoppers.

 

CN and TH&B also had cars built to this design from Canadian Car & Foundry, National Steel Car, and Marine Industries. Orders for both roads continued for similar cars through the early '60s.