Colorado, state in the western United States. The Rocky Mountains, or Rockies, form the most dominant physical feature of the state. To the west of the Rockies lie the high plateaus of the Colorado Plateau, and to the east are the Great Plains. High, rugged mountains and plateaus occupy fully two-thirds of the state, and make Colorado a state of striking beauty. All of Colorado is more than 1000 m (3300 ft) above sea level.
The state, with an average elevation of about 2070 m (about 6800 ft), is the highest of all the states. The mountains and plateaus are rich in gold, silver, and other minerals and are the source of most of the state's water. The mountains have played a major role in the development of Colorado, most recently by attracting a steady flow of tourists, but they have also been a barrier to travel, communication, and settlement. Except for small cities and towns in the sheltered river valleys and mountain basins, most of western Colorado is sparsely populated.
In contrast, eastern Colorado has flat, treeless plains that extend from the Rockies to the Nebraska and Kansas state lines. Cultivated where there is sufficient moisture or irrigation, they consist of croplands and grasslands. On the plains just east of the Rockies is Denver, which is the state capital, the center of the state's largest metropolitan area, and a major city of the Western United States.
The state's name, Colorado, is a Spanish word meaning 'reddish colored.' It was the name early Spanish explorers gave to the Colorado River, which originates in the state. When Colorado became a territory in 1861, William Gilpin, the first territorial governor, formally requested that it be called by the old Spanish name. Colorado was admitted to statehood on August 1, 1876, during the 100th anniversary of the signing of the Declaration of Independence, and today its official nickname is the Centennial State.
