Colorado. Colorado is a state in the Western United States. Artists have often focused on the ruggedness and beauty of Colorado’s terrain. John Casilear's Scene near Greeley (Denver Art Museum) reflects the dramatic mountain vistas of Colorado. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas to the east, and Oklahoma to the southeast. Colorado is noted for its landscape of mountains, forests, high plains, mesas, canyons, plateaus, rivers, and desert lands. It 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. Colorado is the eighth most extensive and 21st most populous U.S. state. The United States Census Bureau estimated the population of Colorado at 5,877,610 as of July 1, 2023, a 1.80% increase since the 2020 United States census. The region has been inhabited by Native Americans and their ancestors for at least 13,500 years and possibly much longer. The eastern edge of the Rocky Mountains was a major migration route for early peoples who spread throughout the Americas. In 1848, much of the Nuevo México region was annexed to the United States with the Treaty of Guadalupe Hidalgo. The Pike's Peak Gold Rush of 1858–1862 created an influx of settlers. On February 28, 1861, U.S. President James Buchanan signed an act creating the Territory of Colorado, and on August 1, 1876, President Ulysses S. Grant signed Proclamation 230, admitting Colorado to the Union as the 38th state. The Spanish adjective colorado means colored red or ruddy. Colorado is nicknamed the Centennial State because it became a state 100 years after the signing of the United States Declaration of Independence. Denver is the capital, the most populous city, and the center of the Front Range Urban Corridor. Colorado Springs is the second most populous city of the state. Residents of the state are known as Coloradans, although the antiquated Coloradoan is occasionally used. Major parts of the economy include government and defense, mining, agriculture, tourism, and increasingly other kinds of manufacturing. With increasing temperatures and decreasing water availability, Colorado's agriculture forestry, and tourism economies are expected to be heavily affected by climate change. he region that is today the State of Colorado has been inhabited by Native Americans and their Paleoamerican ancestors for at least 13,500 years and possibly more than 37,000 years. The eastern edge of the Rocky Mountains was a major migration route that was important to the spread of early peoples throughout the Americas. The Lindenmeier site in Larimer County contains artifacts dating from approximately 8720 BCE. The Ancient Pueblo peoples lived in the valleys and mesas of the Colorado Plateau in far southwestern Colorado.