Cover franked with 1931 pair 1c emerald green & 2c brown GV 'Centenary of Country Union' issue (SG 283/284) tied by GEORGETOWN cds's with superb strike of large '1831 - 1931 Spend your Winter in the tropic of British Guiana Centenary Celebrations Oct. 13-14-15-16-17, 1931' AIRPLANE cachet in purple on reverse. Addressed to USA.