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.
A major producer of natural gas, oil, and agricultural products, Oklahoma relies on an economic base of aviation, energy, telecommunications, and biotechnology. In 2007, it had one of the fastest-growing economies in the United States, ranking among the top states in per capita income growth and gross domestic product growth Both Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly two-thirds of Oklahomans living within their metropolitan statistical areas.