The state was named for the Colorado River, which Spanish travelers named the Río Colorado for the ruddy (Spanish: colorado) silt the river carried from the mountains. The Territory of Colorado was organized on February 28, 1861, and on August 1, 1876, U.S. President Ulysses S. Grant signed Proclamation 230 admitting Colorado to the Union as the 38th state. Colorado is nicknamed the "Centennial State" because it became a state a century after the signing of the United States Declaration of Independence.
The state has a population of approximately 3 million. It is the 32nd most extensive and the 32nd most populous of the 50 United States. Located in the center of the state, Jackson is the state capital and largest city, with a population of approximately 175,000 people.