(Postal Card Essays) American Post Card Co., New York, Forerunner Postal Card Essay (Unstated Value) Dark Green on Buff, mint, folded out for display, Very Fine. UPSS No. UX1E-Ea. Estimate  $200 - 300. This is one of only three cards approved by the U.S. Patent Office. Patent #51,623 was grated to Charles A. Rowland of Clinton, Ill. on December 19th 1865; Rowland later applied to improve his design with Patent #117818 on August 8th 1871, and then assigned his rights to the American Post Card Company. The message is intended to be written on the inner side of the lower panel, then folded and sealed by the top and side flaps. $0 (Image)