Seattle, Wash. Exposition Station, Jun 23, 1909, Alaska - Yukon - Pacific Exposition. Bold strike of flag machine cancel (Bomar S09-04, Langford T26) tying 2¢ Wash-Frank on cover to San Francisco, Cal. with gold "California Building Exposition Grounds" corner card showing Exposition emblem, original enclosure with matching letterhead; cover roughly opened at right and most of sideflap missing, otherwise Very Fine, a Great Exposition Rarity With This Being the Only Known Usage of This Cancel on a Cover. Estimate  $15,000 - 20,000. One of two legitimate postal uses are known, the above cover and a post card, which are both postmarked on the 23rd of June. The post card, which sold at auction in 2003 brought $9,000. It is reported that Langford at one time refused an offer of $25,000 for this cover. $0 (Image)