Below is the introduction of the PSS Official Style Chart, prepared and published by the PSS Specifications committee. Most precancel collectors use this style and numbering system in describing their precancels. The older “Noble” numbering system was owned by Gilbert Noble for use in his catalogs. The PSS system is in the public domain.

If you have an older Noble or Hoover catalog here is The Noble Style Chart and a conversion chart between the two numbering systems.

The PSS Style Chart

The PSS. Official Style Chart is a system of classifying the precanceling overprints applied to United States stamps under authority of the U.S. Post Office with devices designed and authorized for this purpose and manufactured for this purpose. For convenience, it is divided into sections, each representing a mechanical variation in the nature of precanceling devices.

The PSS Style Chart shows the government issued standard types, which covers approximately 90% of all the precancels  from all the towns. The remaining 10% (about 4,000 types) are locally produced types made with approval of the USPS. Illustrations of these so-called L-types can be found in the PSS Town and Type catalog.

Click on the links below to see more information of each style family as well as pictures of sample devices.  Click HERE for the PSS Style Chart

In each section, styles are grouped in approximate chronological order of appearance.

Virtually all U.S. precancel devices are multiple-subject, with the legend (town and state) so sized and spaced to fit once horizontally on each stamp in a sheet of regular- issue U.S. postage stamps. Except for a few handstamps in the early years and electroplates in more-recent years, designed for vertical application (or horizontal application on stamps that are wider than they are tall), the customary 21.5-mm. width of regular-issue stamps has limited the length of the legend. Consequently, towns with few letters in their names could be set in wider letters than towns with many letters in their names. At any period in precancel history, usual practice was to use wider (sometimes spaced) letters for towns with short names, and more-condensed (or lower-case) letters for towns with long names, thus “families” of styles evolved for each period when contracts for devices were awarded. Although such families can be discerned by the student of precancel styles, they have been subordinated to other considerations in developing this system of classification.

In describing individual styles, a few simplifications have been adopted to save space. “Caps” refers to capital letters; “lower-case” refers to small letters but implies the use of caps for initial letters of words. “Face” refers to the width of the strokes of the letters, as in “bold-face”; letters with strokes of varying width are called “shaded”. Successively narrower letters are referred to as “condensed”, “extra- condensed” and “ultra-condensed”. Dimensions in millimeters (mm.) are approximate except when close measurement will help to differentiate styles.