The U.S. government constructed a number of temporary buildings on the National Mall during World War I and II which stood from 1918 until 1971.
They were built due to the urgent need for office space during wartime, but they remained in use during peacetime even though they disrupted the intended layout of the mall according to the McMillan Plan for over half a century.
Its early implementation prior to World War I included initiating the replacement of the old Department of Agriculture Building with the current headquarters, removal of the Baltimore and Potomac Railroad Station, and construction of the National Museum of Natural History.
[1]: 48–52 The entry of the United States into World War I in April 1917 led to an expansion of the federal government, causing urgent need for new office space to be constructed.
Although the buildings were intended to be temporary, the U.S. Commission of Fine Arts by 1918 suggested that they would likely remain in use long past the end of the war.
[6] Beginning in 1929, and accelerating with the inauguration of Franklin D. Roosevelt in 1933, impetus increased for further implementation of the McMillan Plan.
In 1930, the Commission of Fine Arts blamed the temporary buildings for "producing a depressing air of slovenliness" on the Mall.
[13] Although the Navy intended the buildings to provide temporary quarters for the United States military during World War I, the reinforced concrete structures would remain in place until 1970.
Tempo-A was mostly empty and used for storage (furniture) with part of Nixon's reelection campaign occupying it for a short period of time.