This cover originated in the "OFFICE OF SUPERINTENDENT" of the Northern Ogdensburg Railway in the early 1850s. Even with only the embossed corner card, the cover would be a good addition to a collection. However, it has a number of pluses which all add up to a fantastic cover:
(1) nice handstamps of "PAID" and "3" showing the rate that went into effect on July 1, 1851.
(2) red circular date stamp from Odgensburgh
BUT, here are the bonuses:
(3) For some reason, the cover was originally rated as going to Canada. That's why there is a "10" handstamp: to pay the 10c rate to Canada. But it was going to Boston instead and, it seems that the postal clerk realized that and canceled the 10 marking with the 7 bar circle in black. The 7 bar circle was initially sent to post offices that received the 1st issue of US postage stamps in 1847.
(4) Under the postal agreement between the USA and Canada beginning in April 1851, each country would stamp its mail with the country name. In this case the postal clerk used a red "U.States" in ribbon marking.
Finally:
(5) companies such as the Railway that sent a lot of mail sometimes has accounts with the post office. Even though postmasters were not supposed to do it, many kept such accounts. That's the reason for "Charge N. RR" manuscript at the upper right.
A wonderful addition to my Cross Border Collection