(Northwest Territory) "Marietta, 11 Apl.", red manuscript postmark and matching "25" rating on folded letter to Philadelphia, Penn., endorsed "Post" and with letter dateline of "Marietta April 8, 1799"; slight ink erosion in address, a Very Fine example of this rare postmark, unlisted in red by the A.S.C.C. Estimate  $500 - 750. $0 (Image)