1856 (May 20) New York, N.Y. To Copenhagen, Denmark, blue folded unpaid letter sent via Prussian Closed Mail with black "N. York Br. Pkt. '23' May 20" debit exchange cds, carried by Cunard Line "Canada" from Boston, red Aachen (6.3) and blue manuscript "13" sgr. debit rating, converted and rounded up with Danish red crayon "17½" sch. due rating, reverse with "56/9" rating for 65sk. due; vertical file folds, Very Fine. Estimate  $200 - 300. $0 (Image)