Registered/Jul. 4, 1904/Exposition Station/St. Louis, Mo. Bold violet four line Expo. handstamp (Bomar STL04-08B) on cover franked with complete set of 1904 1¢-10¢ Louisiana Purchase tied by Expo. Station Duplex Numeral "1" (Bomar STL04-01) cancel, cover with "California Louisiana Exposition Commission" corner card, trivial, small corner crease affecting 2¢, Extremely Fine, this is the earliest known usage as well as a rare July 4th usage, only 5 covers are recorded with a complete set of Louisiana Purchase and this rare registry marking. Estimate  $1,000 - 1,500. $0 (Image)