Colorado is a U.S. state that encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains. It is part of the Western United States, the Southwestern United States, and the Mountain States. It is the eighth most extensive and the 22nd most populous of the 50 United States. The United States Census Bureau estimates that the population of Colorado was 5,116,796 on July 1, 2011, an increase of +1.74% since the 2010 United States Census.
The state was named after the Colorado River, which early Spanish explorers named the RÃo Colorado for the red colored (Spanish: Colorado) silt the river carried from the mountains. On August 1, 1876, U.S. President Ulysses S. Grant signed a proclamation admitting Colorado as the 38th state. Colorado is nicknamed the "Centennial State" because it was admitted to the Union in 1876, the centennial year of the United States Declaration of Independence.
Colorado is bordered by Wyoming to the north, by Nebraska and Kansas to the northeast and east, by New Mexico to the south, by a small portion of the southern state of Oklahoma, by Utah to the west, and by Arizona to the southwest. The four states of Colorado, New Mexico, Arizona, and Utah meet at one common point known as the Four Corners, which is known as the heart of the American Southwest. Colorado is one of only three U.S. states with no natural borders, the others being neighboring Wyoming and Utah. Colorado is noted for its vivid landscape of mountains, forests, high plains, mesas, canyons, plateaus, rivers, and desert lands.
Denver is the capital and most populous city of Colorado. Residents of the state are properly known as "Coloradans", although the archaic term "Coloradoan" is still used.
