The 1847 Five Cent Benjamin Franklin on the cover above was the first stamp to be issued by the United States Post Office. The stamp was released on July 1, 1847 in New York, NY, however the earliest known usage is July 7, 1847 from New York to Poultney, Vermont. Boston received the stamps on July 2 and the stamp was received by other cities following that date. 

The stamp above is Scott #1a (Dark Brown) and has 4 wide margins including the large sheet margin at bottom. There is a small scissor cut at the top left corner which touches the left margin. The cover and stamp have been canceled with a Red Providence cancel. The Providence cancel on the stamp is faint and hard to make out. The stamp also contains a black script cancel. (I have placed a Blown-up and Sharper Image of the Stamp on a separate page in which the cancel is more clearly visible.) There is an additional Providence Red Cancel at left which is much easier to see. There is also a red 5 to the left of the stamp (For Due 5).

NOTE: Although the stamp itself is without a doubt, authentic and a beautiful bottom-margin copy; there is a possibility that it was placed on the cover afterwards to enhance its value. There are two reasons that I believe this is possible and they are the red due "5" on the cover, which was typically added to mail sent collect. There is also, both a faint red grid and a pen cancel on the stamp itself.

Note: That traces of the red grid overlap the envelope at right center, which makes it more likely that the usage is authentic.

The stamp was designed by James Parson Major from a portrait by James B. Longacre and engraved and printed by the firm of Rawdon, Wright, Hatch, and Edson of New York City. The initials RWH&E are engraved at the bottom center of each stamp. The stamps were printed in sheets with 2 panes of 100 stamps each. 4,400,000 stamps were produced and a quantity of 3,700,000 were issued.

The 1847 imperforate issues were in use until 1851, when they were demonetized and replaced by the 1851 issues. The 5 cent Franklin was used to pay the domestic rate for a 1/2 ounce letter traveling less than 300 miles. The 10 cent Washington paid the domestic rate for a 1/2 ounce letter traveling over 300 miles. The Act of Congress of March 3, 1845 established the rates of postage and the Act of Congress of  March 3, 1847 authorized the Postmaster General  to issue postage stamps. Prior to the Act of 1847, Postmasters in various cities produced their own stamp issues during 1845 and 1846. They were called Postmaster's Provisionals. (See: 1846 Providence Postmaster's Provisional and 1898 Reprint of Providence Postmaster's Provisional)

In 1875, the United States Post Office issued official reproductions of the 1847 stamps. These were made from new dies and were not valid for postal usage. They were issued for the 1876 Centennial Exposition held in Philadelphia, Pennsylvania. The reproductions contain a major difference in the design which makes them readily identifiable from the originals. (See: Comparison of 1847 Original to 1875 Reproduction)

Pen Cancels are the most common type of cancel on this issue. Cancellations in various colors command a premium as do Town Cancels. For example: A Red Town Cancel adds $200 to the catalog value and a Black Town Cancel adds $400 to the value. Orange Cancels add $750 and Green Cancels command a $1500 premium.

Stamps also exist with several types of double impressions or transfers. Some of these are quite common, however a few command premiums of several thousand dollars.

I heartily recommend "Classic United States Imperforate Stamps" by Jon Rose - published by Amos Press (Linn's Stamp News) for further reading about these issues.

THE LETTER
The letter is a three page folded sheet of the same type that was used on stampless covers prior to 1847.  It appears to have been written by a church member living in Providence, Rhode Island to a former church member residing in Newton, Massachusetts. The writer is fond of flowery phrases and makes frequent religious references. He appears to be quite pious,  however he also appears to be quite depressed and feeling very sorry for himself. If the writer were living in today's world, I feel sure he would most likely be under treatment and probably proscribed Prozac. The writer, A. E. Razee, thanks Brother Dibbell for a previously received letter and then goes on and on and on without really saying much of anything.

A few excerpts include these gems:

"by the almost magic of the means of communication can be carried far away on the wings of the wind & give peace comfort and joy & also sorrow and distress to all with whom it comes in contact."
and
"how terrible the deserved punishments the heathen idolaters will use up in the judgment & condemn his people."
and
"The question will then be - What hast thou done with the one, two, five, or ten talents that were committed to your charge? My own miserable reply will be: that I knew what to do, but was afraid & went & hid. I hid my Lord's money & when the master comes may hear - Thou slothful and unfaithful servant, take away from him even that which he seemeth to have and cast him out."
and
"God knows what is best, He setteth up one and putteth down another at his pleasure. If he saw that he could make me a great learned man, give me a sweet pretty wife or a mountain of gold, but his omnificence sees that my own good & his greatest honor & glory would not be advanced thereby and therefore keeps them from me. What is man that God should be mindful of him?" 

For those of you with lots of patience, who would like to browse the actual letter; I have scanned them in at full size on the following pages:

Letter Page 1 
Letter Page 2 
Letter Page 3 

Sources:
Classic United States Imperforate Stamps - Jon Rose 
Scott Specialized Catalog of U. S. Stamps  - 2002 Edition