The rate of air mail postage to the United States was increased to eight cents for the first ounce and six cents for each additional ounce effective July 15, 1964. To facilitate this change in rate, the stock of seven cent aircraft design postage stamp was overprinted with the numeral eight. This overprinted stamp went on sale July 15.
No first day cover service was provided at Ottawa for the overprinted version.
First Day Covers
Air Mail Letter to the US
Ottawa to Dunstable, Mass., July 29, 1964
8 cents air mail letter rate
International Air Mail
St. Charles de Belchasse to Zurich, Switzerland, July 24 1964
Franking : 7 cent jet plane + 8 cent surcharged jet plane (in period)
A lovely usage of the stamps to pay the 15 cent rate