US Transpacific Seapost

For two reasons, Transpacific Seapost is the most straightforward of the six Seapost Services. When a number was assigned to a ship, that number remained with that ship.The second reason is that from 1926 on, all postmarks contained the name of the ship.
In recent years, there have been disagreements about the start of this service. It is now agreed that the first trip was made by the ship "President Jackson" when it left Seattle for Manila on Nov. 11, 1922, with stops in Yokohama, Kobe, Shanghai and Hong Kong. The other four ships should have started operation in July 1923. However, there is a letter from the ship "President Grant" (Seapost number 2) dated January 16, 1923, which seems to disprove this theory.

All five ships of the "Admiral Oriental Line" used TP1 type postmarks. The letters "RMS" in the killer indicate that this service was under the Railway Mail Service.
The post offices on board the ships were considered domestic post offices.

The History of the U.S. Transpacific Seapost Services

From 1921, the Pacific Steamship Co. (the "Admiral Line"), through its subsidiary "Admiral Oriental Line" (initially also using the "Admiral Line" brand), operated five "535-feet" liners from the U.S. Shipping Board on the Seattle to Far East route. All five ships used the TP1 type stamp, which also included the "East"/"West" direction of travel.
A regular service from San Francisco, using the same route but additionally calling at Honolulu, Hawaii, was operated by the "Pacific Mail Steamship Co." for the U.S. Shipping Board in 1924. These ships used TP2 type stamps with the letters "SF" and numbers from 15 to 23. These also included the direction of travel "East"/"West". This stamp no longer includes the letters "RMS" in the killer, so this service was not subject to railroad mail.

In 1924, both companies were acquired by the Dollar Line, and the Admiral Oriental Line, later renamed the American Mail Line, and became a subsidiary of the "American President Lines" in 1938, when the latter was established to continue the business of the bankrupt "Dollar Line". From the beginning of 1926, regular service was established across the Pacific, with bi-monthly departures alternating between Seattle and San Francisco. In 1941, the service ended with the entry of the USA into the Second World War.
The five ships of the "Admiral Oriental Line" (stamp type TP1)
  • Nr. 1 - President Jsckson
  • Nr. 2 - President Grant
  • Nr. 3 - President Madison
  • Nr. 4 - Prsident McKinley
  • Nr. 5 - Prsident Jefferson
The ships of the "Pacific Mail Steamship Company" (stamp type TP2)
  • Nr. SF 15 - President Monroe (?)
  • Nr. SF 16 - President Cleveland
  • Nr. SF 17 - President Garfield (?)
  • Nr. SF 18 - Prsident Wilson
  • Nr. SF 19 - Prsident Lincoln
  • Nr. SF 20 - President van Buren
  • Nr. SF 21 - President Taft
  • Nr. SF 22 - President Pierce
  • Nr. SF 23 - President Hayes (?)

Source reference:

Cockrill, Booklett No 54 und No 55
Hosking, Seaposts of the USA

Postage due commercial postcard with postmark type TP1 to Cockrill with number 1 in CDS. Postmarked 17. April 1924 aboard the steamer "Pres. Jackson" on her eastbound voyage. Addressed to Manila, Philippine Islands. This postcard is on the back of a menu card.
Back of the demand postcard with menu from the dinner of 13. April 1924 and position of the ship on that day, on the Yangtse Kiang.
Postage paid commercial cover with postmark type TP1 to Cockrill with number 2 in CDS. Postmarked 20 February 1925 aboard the steamer "Pres. Grant" on her way west. Addressed to Tokyo, Japan.
Underfranked commercial cover with postmark type TP1 to Cockrill with number 3 in CDS. Postmarked on October 20, 1925 aboard the steamer "Pres. Madison" on her eastbound voyage. Addressed to Gillingham, England.
Postage paid commercial cover with postmark type TP2 to Cockrill with the number SF 15 in the CDS. Postmarked 17. September 1925 aboard the steamer "Pres. Polk"? on her way west. Name of steamer is on back of letter, but is not a guarantee. Addressed to Chicago, Ill.
Postage due commercial postcard with postmark type TP2 to Cockrill with number SF 16 in CDS. Postmarked on July 28, 1925 aboard the steamer "Pres. Cleveland" on her eastbound voyage. Addressed to Lille, France.
Postage paid commercial cover with postmark type TP2 to Cockrill with number SF 21 in CDS. Postmarked 18. August 1924 aboard the steamer "Pres. Taft" on her eastbound voyage. Addressed to Santa Clara, California.
Postage due commercial postcard with postmark type TP2 to Cockrill with number SF 22 in CDS. Postmarked 03. December 1924 aboard the steamer "Pres. Pierce" on her westbound voyage. Addressed to San Francisco, Calif.
Postage paid collector's cover with postmark type TP15 to Cockrill. Postmarked 09 November 1931 on board the steamer "Pres. Coolidge." Addressed to Lancaster, PA.
Underfranked collector's cover with postmark type TP35 to Cockrill. Postmarked 24. January 1936 aboard the steamer "Pres. Hoover. Addressed to Philadelphia, Penna.
Postage due commercial postal stationery with type A postmark to Cockrill with the number 15 in the killer. Postmarked 15. January 1928 aboard the steamer "Pres. Monroe" on her westbound voyage. Addressed to San Francisco, California. With forwarding.
Postage due commercial cover with postmark type A to Cockrill with the number 19 in the killer. Postmarked 14. July 1934 aboard the steamer "Pres. Lincoln" on her eastbound voyage. Addressed to London, England.
Overstamped commercial postcard with type A postmark to Cockrill with number 26 in the killer. Postmarked 28 Feb 1926 aboard the steamer "Pres. Harrison" on her westbound voyage. Addressed to Melrose, Mass.
Underfranked collector's cover with type B postmark to Cockrill with number 16. Postmarked 25. January 1930 aboard the steamer "Pres. Cleveland." Addressed to Philadelphia, Pa.
Postage paid airmail special delivery cover with express postmark type D to Cockrill with number 29 in the killer. Postmarked 12. February 1935 aboard the steamer "Pres. Hoover." Addressed to Hampden, Connecticut.
Postage due commercial postcard with postmark type D to Cockrill with the number 30 in the killer. Postmarked 29 June 1934 aboard the steamer "Pres. Coolidge" on her westbound voyage. Addressed to Chambersburg, Penna.
Postage paid collector's cover postmarked "Crossing the 180° Meridian" and stamped type D to Cockrill with the number 30 in the killer. Postmarked XX. June 194X aboard the steamer "Pres. Coolidge". Addressed to Baton Rouge, La.
Postage due commercial postcard with postmark type F(a) to Cockrill. Postmarked 25 May 1933 aboard the steamer "Pres. Lincoln". Addressed to Coye, France.
Underpaid collector's cover with postmark type Fb-TP81 to Cockrill. Postmarked 10. May 1936 aboard the steamer "Pres. Taft". Addressed to Lima, Peru.
Postage paid commercial cover with postmark type G to Cockrill with the number 22 in the killer. Postmarked Sept. 22, 1936 aboard the steamer "Pres. Pierce" on her westbound voyage. Addressed to St. Louis, Miss.


Copyright Jürgen Kuseler 2021