Altair was laid down as the steel-hulled, single-screw freighter ID-4156 Edisto under a United States Shipping Board (USSB) contract on 18 December 1918 at Seattle, Washington, by the Skinner and Eddy Corporation. Launched on 10 May 1919, Edisto came under naval scrutiny in the 13th Naval District, being given the identification number (Id. No.) 4156 and initially earmarked for potential service as a collier. After a brief period of operation by the USSB, Edisto was transferred to the Navy by executive order on 29 October 1921 and renamed Altair on 2 November 1921. Classified as a destroyer tender, AD-11, the ship was delivered to the Navy on 5 December 1921 and commissioned at the New York Navy Yard the following day, 6 December 1921, Commander James H. Comfort in command.