U.S.P.O., Philadelphia Pa., 1c Black on Blue Glazed (7LB7).
Large bottom margin, frameline at right is complete, traces of others, uncancelled, used on 1850 folded letter to Burlington N.J., blue "Philada. Pa. 5 cts. Jun. 27" integral-rate circular datestamp, stamp has slight rubbed spots in surface color as usual, Very Fine, very scarce (16 reported covers), ex Caspary
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