This stamp has a hidden date on the left side of the building.
It was announced by the Hon. John R. Nicholson, Postmaster General, that effective July 15, 1964, the rate of air mail postage to the United States is to be increased to eight cents for the first ounce and six cents for each additional ounce. This represents an increase of one cent per ounce on the present rate and compares to a straight eight cents per ounce for the United States air mail rate to Canada. Increased cost of mail handling was the reason cited by the Postmaster General for the raise in rates. To facilitate this change in rate, the present stock of seven cent aircraft design postage stamps will be overprinted with the numeral eight. This overprinted stamp will go on sale July 15. The design for the seven cent aircraft stamp will be re-worked to become an eight cent issue, and will be released when stocks of the overprinted stamp have been exhausted.