The single-story Spearfish Post Office (Old) building was constructed in 1940 as the new federal
postal facility for the town of Spearfish. In 1941, a number of offices were added on the ground
floor (basement) to house various federal programs.
The basic organization and ornamentation is typical of the Class C variety of post office
designed for small towns. It is an excellent example of the simplified Classical style of
architecture employed on many small post offices during the Depression.
The building has not been moved. Initial alterations include the construction of the ground floor
offices. Subsequent alterations include modifications in the window bay area to allow for the
installation of additional postal boxes, the modification to the interior entrance vestibule for
weatherproofing, and the installation of a wheelchair-accessible ramp.
The Spearfish Post Office (Old) was vacated as a postal facility in late 1997.