1978 inch Ainch and EAGLE non-denom 1735 Plate Block of 4 x 15 cents US Postage Stamps

On May 22, 1978 in Memphis TN, this first non-denominated stamp was issued when the rate increased in 1978 from 13 to 15. As postal costs increased, the Postal Service began to increase their rates for the various classes of mail. Before becoming effective, however, these rate increases had to be submitted to the Postal Rate Commission for approval. Often, the PRC would take as much as a year conducting studies and compiling data before accepting or rejecting the changes. If the rate increase was approved, the Postal Service then had to rush to design and produce the new stamps. In 1975, after the rate had changed from 10 to 13, the Postal Service printed this non-denominated stamp so it would be ready and waiting for the next rate change. A letter of the alphabet was used to represent the unknown rate, so the stamps could meet customer demand until new definitives bearing the actual rate were printed.