The region that is today the State of Colorado has been inhabited by
Native Americans and their
Paleo-Indian ancestors for at least 13,500 years and possibly more than 37,000 years. The
Lindenmeier site 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. The
Ute Nation inhabited the mountain valleys of the
Southern Rocky Mountains and the
Western Rocky Mountains, even as far east as the Front Range of the present day. The
Apache and the
Comanche also inhabited the Eastern and Southeastern parts of the state. In the 17th century, the
Arapaho and
Cheyenne moved west from the
Great Lakes region to hunt across the
High Plains of Colorado and
Wyoming. The U.S. acquired the territorial claim to the eastern Rocky Mountains with the
Louisiana Purchase from France in 1803. In 1806,
Zebulon Pike led a
U.S. Army reconnaissance expedition into the disputed region. Colonel Pike and his troops were arrested by Spanish cavalrymen in the
San Luis Valley the following February, taken to
Chihuahua, and expelled from Mexico the following July. Under the 1819
Adams-Onís Treaty, the U.S. acquired Florida from Spain while relinquishing claims to lands west of the
100th meridian and south of both the
Arkansas River and the
42nd parallel. The treaty took effect on February 22, 1821. Having settled its border with Spain, the U.S. admitted the southeastern portion of the
Territory of Missouri to the Union as the
state of Missouri on August 10, 1821. The remainder of Missouri Territory, including what would become northeastern Colorado, became an unorganized territory and remained so for 33 years over the
question of slavery. After 11 years of war, Spain finally recognized the independence of Mexico with the
Treaty of Córdoba signed on August 24, 1821. Mexico eventually ratified the Adams–Onís Treaty in 1831. The
Texian Revolt of 1835–36 fomented a dispute between the U.S. and Mexico which eventually erupted into the
Mexican–American War in 1846. Mexico surrendered its northern territory to the U.S. with the
Treaty of Guadalupe Hidalgo after the war in 1848; this included much of the western and southern areas of Colorado. , with the white representing the territory the United States received from Mexico (plus land ceded to the
Republic of Texas) after the
Mexican–American War. Well over half of Colorado was received from this treaty. The
Santa Fe Trail, connected the U.S. to
Santa Fe and the
Camino Real de Tierra Adentro southward. Others traveling overland west to the
Oregon Country, the new
goldfields of California, or the new
Mormon settlements of the
State of Deseret in the
Salt Lake Valley, avoided the rugged
Southern Rocky Mountains, and instead followed the
North Platte River and
Sweetwater River to
South Pass (Wyoming), the lowest crossing of the
Continental Divide between the Southern Rocky Mountains and the Central Rocky Mountains. In 1849, the Mormons of the Salt Lake Valley organized the extralegal
State of Deseret, claiming the entire
Great Basin and all lands drained by the rivers
Green,
Grand, and
Colorado. The federal government of the U.S. flatly refused to recognize the new Mormon government because it was
theocratic and
sanctioned plural marriage. Instead, the
Compromise of 1850 divided the
Mexican Cession and the northwestern claims of Texas into a new state and two new territories, the
state of California, the
Territory of New Mexico, and the
Territory of Utah. On April 9, 1851,
Hispano settlers from the area of
Taos settled the village of
San Luis, then in the
New Mexico Territory, as Colorado's first permanent
Euro-American settlement, further cementing the traditions of
New Mexican cuisine and
New Mexico music in the developing
Southern Rocky Mountain Front. The gold seekers organized the
Provisional Government of the Territory of Jefferson on August 24, 1859, but this new territory failed to secure approval from the
Congress of the United States embroiled in the debate over slavery. The election of
Abraham Lincoln for the President of the United States on November 6, 1860, led to the
secession of seven southern
slave states and the threat of
civil war among the states. Seeking to augment the political power of the
Union states, the
Republican Party–dominated Congress quickly admitted the eastern portion of the
Territory of Kansas into the
Union as the free
State of Kansas on January 29, 1861, leaving the western portion of the Kansas Territory, and its gold-mining areas, as unorganized territory.
Colorado Territory ,
Utah,
Kansas, and
Nebraska before the creation of the
Territory of Colorado On February 28, 1861, outgoing U.S. President
James Buchanan signed an Act of Congress organizing the
free Territory of Colorado which set the current boundaries of Colorado. With resources tied up in the war there was little left over for mines, farms, and infrastructure, and Denver stagnated. On March 26, 1862
John Evans was appointed by Abraham Lincoln as the second governor of the territory. He prompted investment in Denver rail projects, and founded the
University of Denver in 1864. Anti-native sentiment grew during the Civil War years. Exterminationist ideology, led in Colorado by Evans and Chivington, advocated for the total eradication of all native people in the territory. The
Colorado War worsened relations with natives until 1864 when Chivington ordered the
Sand Creek Massacre and Evans was forced to resign the following spring. In the midst and aftermath of the Civil War, many discouraged prospectors returned to their homes, but a few stayed and developed mines, mills, farms, ranches, roads, and towns in Colorado Territory. In 1867, the
Union Pacific Railroad laid its tracks west to Weir, now
Julesburg, in the northeast corner of the Territory. The Union Pacific linked up with the
Central Pacific Railroad at
Promontory Summit, Utah, on May 10, 1869, to form the
First transcontinental railroad. The
Denver Pacific Railway reached Denver in June of the following year, and the
Kansas Pacific arrived two months later to forge the second line across the continent.
Statehood of the
Colorado Central Railroad as photographed by
William Henry Jackson in 1899 The
United States Congress passed an enabling act on March 3, 1875, specifying the requirements for the Territory of Colorado to become a state. On August 1, 1876 (four weeks after the
Centennial of the United States), U.S. President Ulysses S. Grant signed a proclamation admitting Colorado to the Union as the 38th state and earning it the moniker "Centennial State". The discovery of a major silver lode near
Leadville in 1878 triggered the
Colorado Silver Boom. The
Sherman Silver Purchase Act of 1890 invigorated silver mining, and Colorado's last, but greatest, gold strike at
Cripple Creek a few months later lured a new generation of gold seekers. Colorado women were granted the right to vote on November 7, 1893, making Colorado the second state to grant
universal suffrage and the first one by a
popular vote (of Colorado men). The repeal of the Sherman Silver Purchase Act in 1893 led to a staggering collapse of the mining and agricultural economy of Colorado, but the state slowly and steadily recovered. Between the 1880s and 1930s, Denver's floriculture industry developed into a major industry in Colorado. This period became known locally as the
Carnation Gold Rush.
Twentieth and twenty-first centuries in the aftermath of the 1914 massacre. Poor labor conditions and discontent among miners resulted in several major clashes between strikers and the
Colorado National Guard, including the
1903–1904 Western Federation of Miners Strike and
Colorado Coalfield War, the latter of which included the
Ludlow massacre that killed a dozen women and children. Both the 1913–1914 Coalfield War and the
Denver streetcar strike of 1920 resulted in federal troops intervening to end the violence. In 1927, the
1927-28 Colorado coal strike occurred and was ultimately successful in winning a dollar a day increase in wages. During it however the
Columbine Mine massacre resulted in six dead strikers following a confrontation with
Colorado Rangers. In a separate incident in
Trinidad the mayor was accused of deputizing members of the KKK against the striking workers. More than 5,000 Colorado miners—many immigrants—are estimated to have died in accidents since records were first formally collected following an 1884 accident in
Crested Butte that killed 59. In 1924, the
Ku Klux Klan Colorado Realm achieved dominance in Colorado politics. With peak membership levels, the
Second Klan levied significant control over both the local and state
Democrat and
Republican parties, particularly in the governor's office and city governments of Denver,
Cañon City, and
Durango. A particularly strong element of the Klan controlled the
Denver Police.
Cross burnings became semi-regular occurrences in cities such as
Florence and Pueblo. The Klan targeted African-Americans,
Catholics, Eastern European immigrants, and other non-White
Protestant groups. Efforts by non-Klan lawmen and lawyers including
Philip Van Cise led to a rapid decline in the organization's power, with membership waning significantly by the end of the 1920s. By the
U.S. census in 1930, the population of Colorado first exceeded one million residents. Colorado suffered greatly through the
Great Depression and the
Dust Bowl of the 1930s, but a major wave of immigration following
World War II boosted Colorado's fortune. Tourism became a mainstay of the state economy, and high technology became an important economic engine. On September 11, 1957, a plutonium fire occurred at the
Rocky Flats Plant, which resulted in the significant
plutonium contamination of surrounding populated areas. in 1961 From the 1940s and 1970s, many protest movements gained momentum in Colorado, predominantly in Denver. This included the
Chicano Movement, a
civil rights, and social movement of
Mexican Americans emphasizing a
Chicano identity that is widely considered to have begun in Denver. The National
Chicano Youth Liberation Conference was held in Colorado in March 1969. In 1967, Colorado was the first state to loosen restrictions on
abortion when governor
John Love signed a law allowing abortions in cases of rape, incest, or threats to the woman's mental or physical health. Many states followed Colorado's lead in loosening abortion laws in the 1960s and 1970s. Since the late 1990s, Colorado has been the site of
multiple major mass shootings, including the infamous
Columbine High School massacre in 1999 which made international news, where
two gunmen killed 12 students and one teacher, before committing suicide. The incident has spawned many
copycat incidents. On July 20, 2012, a
gunman killed 12 people in a movie theater in
Aurora. The state responded with tighter restrictions on firearms, including
introducing a limit on
magazine capacity. On March 22, 2021, a
gunman killed 10 people, including a police officer, in a
King Soopers supermarket in
Boulder. In an instance of
anti-LGBT violence, a
gunman killed 5 people at a nightclub in
Colorado Springs during the night of November 19–20, 2022. Four warships of the
U.S. Navy have been named the
USS Colorado. The first USS
Colorado was named for the Colorado River and served in the Civil War and later the
Asiatic Squadron, where it was attacked during the 1871
Korean Expedition. The later three ships were named in honor of the state, including
an armored cruiser and the
battleship USS Colorado, the latter of which was the lead ship of
her class and served in
World War II in the Pacific beginning in 1941. At the time of the
attack on Pearl Harbor, the battleship USS
Colorado was located at the naval base in San Diego, California, and thus went unscathed. The most recent vessel to bear the name USS
Colorado is
Virginia-class submarine USS Colorado (SSN-788), which was commissioned in 2018. ==Geography==