Fort Mason, in San Francisco, California originated as a coastal defense site during the American Civil War. The nucleus of the property was owned by John C. Frémont and disputes over compensation by the United States continued into 1968. In 1882 the defenses were named for Richard Barnes Mason, a military governor before statehood. Fort Mason became the headquarters for an Army command that included California and the Hawaiian Islands from 1904 to 1907. In 1912 the Army began building a port facility with piers and warehouses to be a home base for ships of the Army Transport Service serving Alaska, Hawaii, the Philippines and other Pacific Army posts and focus of Army supply for the Pacific.

The San Francisco Port of Embarkation (SFPOE) was a United States Army command responsible for movement of supplies and troops to and from the Pacific during World War II with extensive facilities in the San Francisco area. SFPOE was established 6 May 1932 and disestablished 1 October 1955. It was originally composed of the long term Pacific terminal at Fort Mason that had been the home port and terminal for the Pacific Army Transport Service ships. That facility was far too limited to serve the requirements of a full port of embarkation. In 1940 the port began expansion to include Army owned and leased facilities throughout the San Francisco Bay area and for a time sub ports at Seattle and Los Angeles. Those eventually became separate commands as the Seattle Port of Embarkation and Los Angeles Port of Embarkation.