Detroit "Steamboat Due 6 Cts", oval rating handstamp on circa 1864 cover addressed to Governor Henry H. Crap at his home in Flint Mich., bearing 3¢ rose (65) tied by "Detroit Mich May 23" duplex; treated as a steamboat letter with 6¢ and 3¢ prepayment ignored; no flap, tiny edge tear, Very Fine. Estimate  $300 - 400. From July 1st 1863, steamboat letters were charged double the 3¢ letter rate and any prepayment on insufficiently prepaid letters was ignored. Henry H. Crap was Governor of Michigan from 1864 to 1868. $0 (Image)