Designed by Gilbert Stanley Underwood, the Terminal Annex was built by the Sarver & Zoss contracting firm from 1939 to 1940.

[5] At the formal dedication ceremony in June 1940, the postmaster called the annex a symbol of the achievements of democracy, opening at a time when the monuments of Europe were "being ground in the dust.

[14] Accordingly, the Postal Service Board of Governors in 1984 approved the construction of a new $151 million general post office in South Los Angeles.

When the Postal Service moved out of the building in 1995, it was used as a film location for the motion picture Dear God in 1995 and for the CBS television series EZ Streets in 1996.

[19] The Terminal Annex building was listed on the National Register of Historic Places in 1985 based on its architectural style.