Santa Fe Freight Car Classification System
In 1903 Santa Fe reorganized and classified its freight car fleet
into the system used to the end of the Santa Fe. A two letter abbreviation
was assigned to each type of car and a sequential number (originally
a letter) was assigned to each design group in the class.
Cars were only re-classified when they were modified or rebuilt
for use in a different service. Cars were often rebuilt or upgraded,
e.g., rebuilding wooden cars with steel, and remained in the same
class. Some classes contained a single car, and others were empty.
The empty classes were assigned to orders or proposed orders for
cars that were not built.