The term "Centennial State" refers to the state of Colorado, which was admitted to the United States on August 1, 1876, exactly 100 years after the signing of the Declaration of Independence. This nickname reflects the state's historical significance and its celebration of the centennial anniversary of the nation. Colorado is known for its diverse geography, which includes the Rocky Mountains, high plains, and desert lands. The state is famous for outdoor activities such as skiing, hiking, and mountain biking, attracting millions of visitors each year to its national parks and recreational areas.