The area currently occupied by the U.S. State of Colorado has undergone numerous changes in occupancy, territorial claims, and political designations. Paleoamericans entered the region about 11,500 BCE, although new research indicates the region may have been visited much earlier. At least nine Native American nations have called the area home. Although Europeans may have entered the region as early as 1540, the first European fort was not constructed until 1819, and the first European town was not established until 1851, primarily due to the opposition of the Ute people. Spain, France, Mexico, and the Republic of Texas have all claimed areas of future state. The United States first claimed an eastern portion of the future state with the Louisiana Purchase of 1803. The United States surrendered the portion of the region south and west of the Arkansas River to the Spanish Empire with the Adams–Onís Treaty in 1821. The United States completed its acquisition of the region with the Treaty of Guadalupe Hidalgo that ended the Mexican–American War in 1848. The United States created the free Territory of Colorado in 1861 following the Pikes Peak Gold Rush. The Territory fought for the Union during the American Civil War despite many of its founders being natives of slave states or territories. The Territory of Colorado joined the Union as the State of Colorado in 1876, the centennial year of the United States.
Indigenous peoples
Indigenous peoples who have lived in the area of the present State of Colorado:
Paleoamericans
Pre-Clovis culture
Clovis culture
Folsom culture
Plano cultures
Archaic Period
Apex complex
Archaic–Early Basketmaker Era
Mount Albion complex
Post-Archaic Period
Apishapa culture
Dismal River culture
Panhandle culture
Sopris phase
Plains-Woodland
Ancestral Puebloans
Mesa Verde
Native American Nations
Apache Nation
Jicarilla Apache
Arapaho Nation
Northern Arapaho
Southern Arapaho
Cheyenne Nation
Comanche Nation
Kiowa Nation
Navajo Nation
Pawnee Nation
Shoshone Nation
Eastern Shoshone
Ute Nation
Capote Ute band — native to the upper Rio Grande valley and the San Luis Valley. Mouache Ute band — native to the eastern slope of the Southern Rocky Mountains, from Denver south into New Mexico. Parianuche Ute band, later known as the Grand River or White River band — native to the upper Colorado River valley. Tabeguache Ute band, later known as the Uncompahgre band — native to the Gunnison River and Uncompahgre River valleys. Weeminuche Ute band — native to the San Juan River basin in Colorado and New Mexico. Yamparica Ute band, later known as the White River band — native to northwestern Colorado. Uintah Ute bands including the bands named Cumumba, Pahvant, San Pitch, Sheberetch, Tumpanawach, and Uinta-ats — native to eastern Utah.
Early European claims
Early Iberian claims in the New World: