On 16 November 1921, the ship was classified as a transport, AP-4. Departing Philadelphia on 24 November 1921 with military and civilian passengers, as well as a senatorial party, Argonne's maiden voyage and shakedown took the ship to Port-au-Prince, Haiti; St. Thomas, Virgin Islands; Ponce, Puerto Rico; and Santo Domingo City, Dominican Republic; before she put into Hampton Roads on 22 December. Subsequently returning to Philadelphia for post-shakedown availability, Argonne proceeded to the Panama Canal via Charleston, South Carolina, and after a stop at Mare Island continued across the Pacific to Cavite, in the Philippines, on her first voyage to that part of the globe.