How to Identify Precanceled Envelopes

by Michael Hynes

Like anything else, getting started in a new collecting field always seems daunting. The field of Precanceled Envelopes may look to be very complicated but actually is very simple after you learn the four different identifying characteristics. They are the type of precancel, the die type, the envelope style, and the watermark.

Type of Precancel

Several things need to be noted to identify the precancel type on an envelope. Each of these add up to form the type.

Type of Printing:

1 – Large serifed capital letters
2 – Small serifed capital letters
3 – Small san-serifed capital letters

State Name Designation:

a – Abbreviated state name
b – Unabbreviated state name

Code number used for the Proper P.L & R. phrase:

  1. (Sec. 435 1/2 P.L. & R.)
  2. (Sec. 562 P.L. & R.)
  3. (Sec. 34.66 P.L. & R.)
  4. (Sec. 34.65(3) P.L. & R.)
  5. (39 C.F.R., 34.65(e)
  6. (39 C.F.R., 34.66)
  7. (Non-Profit Organization)
  8. (Bulk Rate)

With the above identified, you will end up with a number, letter, number combination, i.e. 1a1, 1b2, 1b2, 3a3, 3a7, etc. Here are some examples:

Type 1a1

Type 1a2

Type 2a1

Type 2a2

Type 3a2

Type 3a3

Type 3a4

Type 3a5

Type 3a6

Type 3a7

Type 3a8

Type of Die

Nine different dies have been used on precanceled envelopes. They are typically identified as the following:

Die Description Example
A 1 cent, Circular Die A of 1916-50. Round “C” of “CENT”  
E 1 cent, Circular Die C of 1916-50. Rectangular “C” of “CENT”  
O 1 cent, Green Oval die of 1950  
X 1 1/2 cent, Brown Oval die of 1950  
1A 1 1/4 cent, Die A, Turquoise Oval die of 1960. Thin left leaves.  
1B 1 1/4 cent, Die A, Turquoise Oval die of 1960. Fat left leaves.  
2C 2 cent, Die C, Red Oval of 1950  Sorry, No Picture. Similar to 2D.
2D 2 cent, Die D, Red Oval of 1950  
2+ 2 1/2, cent Blue Oval of 1960  

Envelope Size, Color, Knife, Gum, and Window

Envelope Size:

Government issued precanceled envelopes only came in 4 sizes:

  • Size 5 89 mm x 160 mm
  • Size 6 3/4 92 mm x 165 mm
  • Size 8 (10) 105 mm x 241 mm
  • Size 13 98 mm x 171 mm

Envelope Color:

Until December 12, 1943 precanceled envelopes where made in 3 colors: White, Amber, and Blue. After that date, all were White.

Window Envelopes:

Precanceled envelopes have been issued with a glassine window in the face, so that an address printed on the enclosure can be read through the window. These envelopes were typically un-gummed and low-back types. After December 31, 1949, window precanceled envelopes were discontinued.

Envelope Gum and Knife:

The earliest government precanceled envelopes were issued with a gummed flap. Beginning in January 1930 all were issued un-gummed. The knife refers to how the envelope was cut in it’s manufacture. For precanceled envelopes only two varieties exist: high-back and low-back.









High-back: the underfold of the envelope extends nearly to the top of the back of the envelope.









Low-back: the underfold extends but little more than half way up the back of the envelope.

Using all of the above characteristics, collectors have put together a system to describe each envelope. This code is used instead of the more widely known Thorp system, since precanceled envelope collectors began collecting them without knowledge of the Thorp system. The system first devised by D.D. Berolzheimer is shown below:

No. Color With Gum No. Color No Gum No. Color Window/No Gum
1 White Low Back 7 White Low Back 13 White Low Back
2 Amber Low Back 8 Amber Low Back 14 Amber Low Back
3 Blue Low Back 9 Blue Low Back 15 Blue Low Back
4 White High Back 10 White High Back 16 White High Back
5 Amber High Back 11 Amber High Back 17 Amber High Back
6 Blue High Back 12 Blue High Back 18 Blue High Back

 Size 5 (89mm x 160mm)


No. Color With Gum No. Color No Gum No. Color Window/No Gum
21 White Low Back 27 White Low Back 33 White Low Back
22 Amber Low Back 28 Amber Low Back 34 Amber Low Back
23 Blue Low Back 29 Blue Low Back 35 Blue Low Back
24 White High Back 30 White High Back 36 White High Back
25 Amber High Back 31 Amber High Back 37 Amber High Back
26 Blue High Back 32 Blue High Back 38 Blue High Back

 Size 8 (105mm x 241mm)

No. Color With Gum No. Color No Gum No. Color Window/No Gum
41 White Low Back 47 White Low Back 53 White Low Back
42 Amber Low Back 48 Amber Low Back 54 Amber Low Back
43 Blue Low Back 49 Blue Low Back 55 Blue Low Back
44 White High Back 50 White High Back 56 White High Back
45 Amber High Back 51 Amber High Back 57 Amber High Back
46 Blue High Back 52 Blue High Back 58 Blue High Back

 Size 13 (98mm x 171mm)

No. Color No Gum
66 White High Back

Size 6 3/4 (92mm x 165mm)

Type of Watermark

Watermarks were used to identify the envelope contract used in the manufacture of the envelope. To find the watermark, just hold the envelope up to a very bright light opening the flap, with the back towards the lamp. Here are all of the watermarks used in Bureau Precanceled envelopes:

Putting it all together:

Precanceled envelopes are described in the following manner, best described with an example:


1a1  E   30 30a
(a)   (b)  (c) (d)

(a) Precancel Type In this case it is a Type 1 with state name abbreviated and Sec. 435 1/2 P.L. & R. legend.

(b) Envelope Die In this case it is the 1c circular Die E.

(c) Envelope Designation This is obtained from the envelope numbering system indicated above. In this case 30 stands for size 8, white paper, high back with un-gummed flap.

(d) Watermark The 30a indicates a 1929 watermark with date at bottom and altered as shown on the watermark chart.


  1. Precanceled Envelopes of the United States, 3rd Edition, 2003 by David W. Smith, Published by the Precancel Stamp Society.
  2. A Guide to Precanceled Stamped Envelopes, 1956, by Gilbert W. Noble.