#63 1861 1c Blue, Vertical Strip of Four, Tied by Four Grid Cancel on Cover to Boston, Manuscript "DUE 6."

Rated for prepayment of the 1c carrier fee to-the-mails plus 3c per 1/2 oz. postage. Likely a double-weight letter that was short paid and marked "Due 6" in manuscript to account for the 3c deficiency plus a 3c fine, in accordance with postal regulations effective from July 1, 1863, to May 1, 1865.