When Colorado CO entered the Union, it was known as  the Centennial State because it was the 100th anniversary of the signing of the Declaration of Independence.  The large red "C" on the Colorado flag, designed by Andrew Carlisle Carson, stands for Colorado, Centennial and for Columbine, the Colorado state flower.  The colors of theColorado state flag parallel the blue, white and gold of the flower.  The gold color also recalls the year-round sunshine as well as the founding of Denver during the gold rush of 1858.  Colorado State Flag Adopted:  1911