10c Black (2).
Position 23L, large margins to just in, bright shade, tied by blue "Philada. Pa. 5cts. Apr. ?" integral-rate circular datestamp on folded letter datelined "Philad. 4th April 1851"
and addressed to Montreal, Canada,
also with sender's manuscript "Paid to the lines"
notation at top, red "Montreal L.C. AP 11, 1851" receiving backstamp, minor splitting along vertical file fold which is well away from stamp, Very Fine, the earliest recorded use of the 10c 1847 under the new U.S.-Canada treaty -- effective April 6, 1851, a new rate was established between the United States and Canada; mail was no longer prepaid just to the border, but the sender was apparently unaware of the impending rate change and marked it "paid to the lines"; by the time his letter arrived in Canada the new treaty was in effect, so it was considered fully prepaid to destination -- ex Hart and Mirsky, illustrated and described in an article in Chronicle
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