To prevent the thieves from transporting stamps out of Kansas and Nebraska and selling them elsewhere, the Post Office tried overprinting the letters Kans. on stamps slated for sale in Kansas and Nebr. on stamps that were to be sold in Nebraska. All post offices in Kansas and Nebraska received overprinted stamps except for Kansas City, Topeka, and Wichita, Omaha, and Lincoln There larger post offices were not included as security at those post offices was considered sufficient. Higher values were not included as the overprints could only be performed by rotary press.

This was an experiment, which if successful would be extended to all states. These overprints would be valid throughout the United States. However it did not prove a success as many postal workers in the USA were not aware of these overprints and would not accept them as valid postage.

I should note that I have not yet seen a fake overprint on the one cent denomination, no doubt due to its low value.

The top image is a first day cover of #658, dated May 1st, 1929. This was the first date it was issued at the Philatelic Bureau in Washington DC. The true first date of issue was April 15th, 1929, the day it was issued in Kansas, as shown in the bottom image.

The overprints were commonly faked. The amateur simply used a typewriter. The professional fake was a bit more advanced. Here are some clues to a stamp having a fake overprint.

• On mint stamps you will NOT see the impression of the stamp in the gum
• The perforation can ONLY be 11 x 10½
• There can only be 14 gum ridges and one or two gum breakers (see below)
• They can only be the shades of the 1926 #632 to #642
• The overprint will be underneath, not on top of a cancellation
• On plates, check the plate numbers listed for the overprints on this site
• Dropped or raised letter or period (see below)
• The typeface is incorrect (see image (above)

The faint ridges seen horizontally across the gum are called gum breakers. They were applied by the Bureau in order to prevent the stamps curling. Sometimes they are so faint they can only be detected by running your finger over the gum. The gum breakers on the Kansas and Nebraska overprinted stamps are 22mm apart. Which means only one gum breaker, or two if the breakers are at the very top and bottom of the gum, should be present. The example above is NOT an overprint as the gum breakers because the gum breakers should be further apart.

One of the most easily faked stamps, all one needed was a typewriter. Fortunately the period on most typewriters, at the time, was improperly aligned with the characters. The stamp above has a raised period, thereby it cannot be a genuine overprint.