Offered here is an original Colorado Centennial-Bicentennial Commission First Day of Issue Cover with a post mark dated May 21, 1977 and an intact 13 Cent Colorado Stamp. Two imprinted silver colored disks read 1876-1976, commemorating 1876 when Colorado joined the Union, with a Horseback Frontiersman. Great display piece of Colorado 1977 First Day Issue history. Thanks for looking!