Ordered by E. H. Harriman's Pacific Mail Steamship Co. for its San Francisco-Far East service, Mongolia was laid down as Minnelora on 7 June 1902 in Shipway J at New York Shipbuilding in Camden, New Jersey. The 615-foot vessel was contract #5 for the young company, and the first passenger-cargo liner built by the firm. A sister ship, SS Manchuria, was ordered at the same time and delivered three months after Mongolia. The accommodations of both ships reflected the importance of emigration to shipping lines of the era: 350 first-class, 68 second-class, and 1,300 steerage.