Faced with an aging fleet and growing wartime traffic, the Southern Pacific
began a major caboose building program in 1917. The new design was the
first with a Harriman Common Standard class designation, C-30-1, to
indicate car type (C for caboose), weight (30 tons) and design series
number (1 for first series). Though similar to earlier CA series cars, the
new design incorporated several improvements including a riveted steel
underframe. This made the cars sturdier and safer, especially on runs where
helpers pushed trains upgrade. In the next ten years, SP built over 600
C-30-1s, making them the largest group of cabooses in service on the
railroad and its subsidiary lines. They were also long-lived, working all
types of freight assignments into the 1960s.
