G.B. Post & Co. "Via Panama.", perfect strike of straightline handstamp on buff cover addressed to Medford Mass. with dark blue "G.B. Post & Co., Commission Merchants, San Francisco" octagonal embossed cameo on flap, manuscript "U.S. Mail Packet Sonora, Sept 30. 1854" endorsement and bearing 3¢ dull red (11A) vertical pair, positions 15-25L2L, cancelled by matching manuscript "X" cancels prepaying the 6¢ over 3,000 mile rate; slightly rough opening at top, Very Fine. Estimate  $3,000 - 4,000. THE ONLY RECORDED EXAMPLE OF G.B. POST & CO. "VIA PANAMA" DIRECTIONAL HANDSTAMP. G.B. Post & Company of San Francisco were mail agents for the Hawaiian Post Office and handled other mails. They apparently utilized a "Via Panama" handstamp to ensure their mail went by this route rather than via Nicaragua. It is also common practice to endorse letters with the name and sailing date of the steamboat carrying the letters from San Francisco to Panama City.Carried by the Pacific Mail Steam Ship "Sonora" leaving San Francisco Sept. 30th and arriving at Panama on October 4th. Put onto the United States Mail Steamship "George Law" leaving Chagres October 17th to New York arriving October 27th 1854. $0 (Image)