PAGES WITH UNTAGGED STAMPS
It seems strange to end a discussion where we started except by isolating out untagged stamps as outliers. However, here we are 35-years after the first tagged stamp was introduced into an untagged world. Untagged was initially reserved for "precancels" in the earlier years but now includes:  service inscribed;  low value (under 10˘); and  Expedite Mail stamps.
Service inscribed stamps encompass Bulk Rate, Nonprofit, Nonprofit - Carrier Route Sort, Presorted First Class, ZIP+4, etc. Starting in 1985, the USPS considerd service inscriptions as precancels and issued them untagged. Early precancels were characterized by heavy black parallel lines (with or without service inscription) and were not tagged since mail affixed with them did not go through the normal mail stream. In 1976, the USPS started producing coils with service inscriptions - Drum "Bulk Rate" [76-13]; this issue was also produced in an untagged precancel version which carried the standard heavy lines across the front of the stamp. The ensuing service-inscribed stamps were tagged and most had untagged precancels (with two heavy black parallel lines).
In 1984 the USPS released Railroad Caboose [84-07], a service inscribed stamp, and was originally believed to be the first service-inscribed stamp issued untagged without a standard precancel version; however, the untagged version (PN2) was reissued after the fact in 1991. In 1985, the USPS did issue service-inscribed untagged stamps, 21.1˘ USA Letters ZIP+4 [85-48] and 18˘ Washington Presorted First Class [85-51]; this signaled a change in post office policy and what was to become the new wave of untagged precancels without standard black parallel-lined precancels. The USA Letters was issued with and without service inscription - and why you ask? ... under certain conditions, users of this tagged non service-inscribed stamp could use it for first-class mail (and save a whole 9/10 ˘). If this seems strange, the 18˘ Washington was also issued in both service-inscribed and non service-inscribed versions where the tagged non service-inscribed stamp covered the new extra-ounce rate for first class letters. However, the new extra-ounce rate applied only to letters sent to Canada and Mexico; the rate remained 17˘ within the US! Star Route Truck is the first totally untagged service-inscribed precancel without back bars or tagged versions supporting it.
In 1990 the USPS deemed it appropriate to eliminate the cent sign from low valued stamps [Marin 90-06] and added a "0" in front so users wouldn’t have to be attuned to our currency system. Now that’s progress! Effective January 1991, the USPS made another decision to stop tagging stamps with a face value below 10˘ in an effort to cut down on short-paid mail pieces (deliberate under-paying of correct postage). It was unprofitable as well as stupid to counterfeit low values since short-paying accomplished the same thing without any penalty. By not tagging these low values, at least one high-value tagged stamp would have to be affixed if the letter was to go through the normal mail stream and not be subjected to clerk scrutiny after being rejected by the sensing device. The 04 Steam Carriage [91-06] was in production at this time; so, BEP changed in mid-stream and started producing non-tagged versions - the reason for the two versions on this issue. My Page has "tagged" stamps only.
Two interesting low-valued stamps emerged in 1991 because of 1991 rate hikes. Many of the existing "service inscribed" stamps were fractional valued and when prices increased, remained fractional valued. To overcome the problem of printing many fractional varieties, the USPS opted to issue two whole-numbered stamps, one 5˘ for non-profit bulk mailers and one 10˘ for third class and first-class presort mailers. These stamps had different inscribed slogans : Additional Nonprofit; Postage Paid for non-profit bulk mail and Additional Presort; Postage Paid for first and third class presort mail. These "false franking" stamps required the mailer to pay the difference between the face value and actual postage at the time of mailing. Also the wording "Bulk Rate" or "Presorted First Class" had to be added to the envelope. These are interesting stamp Pages and collectable delights. We have them affixed to Souvenir Pages with FDOI cancels. Check your pages 91-24 (Canoe and Trailer) and 94-13 (Tractor Trailer).
In 1995 the USPS started replacing all low-valued stamps which carried a "0" prior to the number [Circus Wagon 95-08] and restored the cent sign (05 -> 5˘). The USPS stated that users and postal clerks were getting the low-valued stamps confused for higher-valued stamps (˘ for $). Only in America. The dumbing down is now complete. Vote for the liar, he promises more. The USPS produced these low-valued issues untagged only.
The last category of untagged stamps, Expedite Mail high value issues, were issued untagged since these are mainly used on a hand-back basis. Check Pages $10.75 Express Mail [85-25, 88-26]), $9.95 Express Mail [91-29] and $14 Express Mail - International [91-42].
1. Linn’s STAMPS THAT GLOW (1990) by Wayne Youngblood
2. Linn’s U.S. Stamp Year Book, years 1983 - 1997
3. The Postal Service Guide to U.S. Stamps, 24th Edition 1998
4. USA PHILATELIC (USPS catalogues)
5. Linn’s Stamp News and on-line service
6. ASPPP Journal, Volume 12, No. 4
7. USPOD Information service release No. 22, dtd January 26, 1966
8. Scott’s Catalog
9. My collection