VERY FINE. A BEAUTIFUL AND RARE FIRST DAY USE OF THE ONE-CENT PANAMA-PACIFIC EXPOSITION ISSUE. ONLY TWELVE ARE KNOWN.
From February 20 to December 4, 1915, the Panama-Pacific Exposition was held in San Francisco, to commemorate Balboa's discovery of the Pacific Ocean and to celebrate the opening of the mankind's greatest engineering achievement, the Panama Canal. As early as 1912 commemorative stamps were planned to promote the exposition, in 1c, 2c, 5c and 10c denominations. Special cancels to promote the exposition were produced for certain west coast post offices.
The stamps were in use for over three years. However, only twelve known First Days are recorded -- six are on cards and six are on covers.
With 1987 AFDCS certificate.