Colorado is the 38th State Admitted to the Union
After its first bid for statehood was vetoed by President Andrew Johnson, Colorado entered the Union on August 1, 1876, the year the United States celebrated its centennial.
Thus, the thirty-eighth state is known as the Centennial State.
Among the early inhabitants of the land encompassed by Colorado were the Anasazi cliff dwellers. They were forced by drought and other factors to abandon their Mesa Verde homes in the late 1200s. At the time of European exploration and settlement Colorado's population was made up of Arapaho, Cheyenne, and Ute peoples. Their territory was explored by the Spanish who, after Napoleon's conquest of Spain, turned over its title to the French.
The United States acquired the eastern part of Colorado in 1803 through the Louisiana Purchase and the western portion in 1848 through the Treaty of Guadalupe Hidalgo. In 1850, the federal government also purchased a Texas claim in Colorado. This combined property eventually became the Colorado Territory in 1861.
The United States Congress passed an enabling act on March 3, 1875, specifying the requirements for the Territory of Colorado to become a state. On August 1, 1876 (28 days after the Centennial of the United States), U.S. President Ulysses S. Grant signed a proclamation admitting the State of Colorado to the Union as the 38th state and earning it the moniker "Centennial State". The discovery of a major silver lode near Leadville in 1878, triggered the Colorado Silver Boom. The Sherman Silver Purchase Act of 1890 envigorated silver mining, but the repeal of the act in 1893 led to a major collapse of the mining and agricultural economy of the state.
Denver is a beautiful city of some 75,000 inhabitants, built mostly of stone and brick. It contains the usual amount of fine buildings. One in particular we are lead to observe, and that, Tabor's Opera House, the largest in the world, excepting one in Paris, France. This building cost $850,000. The County Court House occupies an entire block, with buildings and ground. There are two large smelting works here… ”— Sue A. Sanders, A Journey to, on and from the "Golden Shore"