The state was named for the Colorado River, which Spanish travelers named the Río Colorado for the ruddy 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.
Colorado is bordered by Wyoming to the north, Nebraska to the northeast, Kansas to the east, Oklahoma to the southeast, New Mexico to the south, Utah to the west, and touches Arizona to the southwest at the Four Corners. Colorado is noted for its vivid landscape of mountains, forests, high plains, mesas, canyons, plateaus, rivers, and desert lands. Colorado is considered part of the western or southwestern United States, and one of the Mountain States.
Denver is the capital and most populous city of Colorado. Residents of the state are known as Coloradans, although the term "Coloradoan" has been used archaically and lives on in the title of the Fort Collins Coloradoan newspaper.
Colorado is notable for its diverse geography, which includes alpine mountains, arid plains, deserts with huge sand dunes, and deep canyons. The borders of Colorado were originally defined to be lines of latitude and longitude, making its shape a latitude-longitude quadrangle which stretches from 37°N to 41°N latitude and from 102°03'W to 109°03'W longitude (25°W to 32°W from the Washington Meridian). Colorado, Wyoming and Utah are the only states which have boundaries defined solely by lines of latitude and longitude.
The summit of Mount Elbert at 14,440 feet (4,401.2 m) elevation in Lake County is the highest point in Colorado and the Rocky Mountains of North America. Colorado is the only U.S. state that lies entirely above 1,000 meters' elevation. The point where the Arikaree River flows out of Yuma County, Colorado, and into Cheyenne County, Kansas, is the lowest point in Colorado at 3,317 feet (1,011 m) elevation. This point, which holds the distinction of being the highest low elevation point of any state, is higher than the high elevation points of 18 states and the District of Columbia.