Back-of-Book (BOB) stamps in the United States refer to a category of postage stamps that fall outside the traditional or regular postage issues. These stamps serve specific purposes and are often associated with special services or fees. The United States has issued various types of BOB stamps over the years, and they are listed in the Scott Catalog under specific prefixes. Here are some of the major types of BOB stamps in the United States:

1. Postage Due Stamps (J1-J109): The Postage Due series, as listed in the Scott Catalog, comprises stamps issued to collect unpaid postage on underpaid mail. The article explores the evolution of these stamps from the first issues in the late 19th century to the modern era, highlighting changes in design and rates.

2. Special Delivery Stamps (E1-E23): Special Delivery stamps, denoted by the “E” prefix in the Scott Catalog, were introduced to expedite the delivery of time-sensitive mail. The article discusses the inception of this service and the various designs that graced special delivery stamps over the years.

3. Official Stamps (O1-O150): Official stamps, identified by the “O” prefix, were used by government agencies for official mail. The article delves into the history of official stamps, examining their issuance, purpose, and the distinct designs that set them apart.

4. Parcel Post Stamps (Q1-Q12): The Parcel Post series, designated by the “Q” prefix, marked a significant development in the postal system, allowing the mailing of parcels at specified rates. This section explores the introduction and evolution of parcel post stamps, including the notable issues listed in the Scott Catalog.

5. Registration Stamps (F1-F4): Registration stamps, bearing the “F” prefix, were used to indicate the payment of fees for registering mail. The article examines the limited but historically significant range of registration stamps and their role in securing the transmission of valuable items.

6. Special Handling Stamps (QE1-QE4): Special Handling stamps, with the “QE” prefix, were introduced for mail that required special care in handling. This section details the creation and usage of these stamps, offering insights into the postal services’ commitment to meeting specific mailing needs.

7. Revenue Stamped Paper (RS1-RS81): An integral part of the back-of-book category, revenue stamped paper includes legal and financial documents imprinted with revenue stamps. The article explores the varied uses of revenue stamped paper and its intersection with the revenue stamp collecting hobby.