The Territory of Colorado was an organized incorporated territory of the United States that existed from February 28, 1861, until August 1, 1876, when it was admitted to the Union as the 38th State of Colorado.

The territory was organized in the wake of the Pike's Peak Gold Rush of 1858–1862, which brought the first large concentration of white settlement to the region. The organic legislative act creating the slave-free Territory of Colorado was passed by the United States Congress and signed by 15th President James Buchanan (1791-1868, served 1857-1861), into law on February 28, 1861. During that period which at the same time (since beginning with South Carolina the previous December 1860), the secession of seven, later eleven southern slave states had been occurring those several months proclaiming / forming a new independent Southern government of the Confederate States of America (which eventually grew in the next year by two more divided state governments to thirteen in the Confederacy, with two alleged western territories) that precipitated the American Civil War of April 1861 to June 1865. The boundaries of the Federals' newly designated Colorado Territory were essentially identical with those of the current / modern State of Colorado, with lands taken from the four surrounding previous Federal territories of Nebraska, Kansas, New Mexico, and Utah (Deseret) established during the 1850s. The organization of the new territory helped solidify Union / Federal control over the mineral-rich area of the western Rocky Mountains. Statehood was regarded as fairly imminent with the expected growth in the constantly westward moving population, but the local territorial ambitions for full statehood were thwarted at the end of the war in 1865 by a constitutional veto by newly sworn in 17th President Andrew Johnson (1808-1875, served 1865-1869), who was a War Democrat who succeeded to the office after briefly only serving one month as Vice President after Lincoln's assassination that April. Statehood for the territory was a recurring issue during the subsequent Ulysses S. Grant presidential administration, with Republican 18th President Grant advocating statehood against a less willing Congress during the following post-war Reconstruction era (1865-1877). After a long constant lobbying campaign, the old Colorado Territory finally ceased to exist after only 15 years when the State of Colorado was admitted to the Union as the 38th state during the American Centennial celebrationn in August 1876

East and West of the Continental Divide, which split the North American continent and the Rocky Mountains, plus the new territory which included the western portion of the previous Kansas Territory, as well as some of the southwestern decade-old Nebraska Territory, and a small parcel of the northeastern corner of the New Mexico Territory. On the western side of the Divide, the territory included much of the eastern older Utah Territory, all of which besides its substantial while Mormon / L.D.S. population especially around the capital of Salt Lake City, was strongly controlled by the Ute and Shoshoni native tribes The Eastern Plains were held much more loosely by the intermixed Cheyenne and Arapaho, as well as by the Pawnee, Comanche and Kiowa. In 1861, ten days before the establishment of the Federal territory, the Arapaho and Cheyenne agreed with the United States government in the East in Washington, D.C. to give up most their areas of the Great Plains to white settlement but were allowed to live in their larger traditional areas, so long as they could tolerate homesteaders near their camps. By the end of the American Civil War in 1865, the Native American presence had been largely reduced or pacified through military action or peace treaties on the High Plains.

Historical population

Year	Pop.	±%
1860	34,277	—
1870	39,864	+16.3%
Source: 1860–1870;

The land that eventually became the Colorado Territory fell under the jurisdiction of the United States in three separate stages: the Louisiana Purchase in 1803 (as adjusted by the 1819 Adams–Onis Treaty), then the Annexation of Texas in 1845, and finally the Mexican Cession in 1848. The land claims of Texas were initially controversial. The border between the U.S. and Mexico was redrawn in 1848 with the Treaty of Guadalupe Hidalgo at the end of the Mexican–American War, and the final borders of the state of Texas were established by the Congressional Compromise of 1850.

The land that was eventually defined as the Colorado Territory was home to a number of indigenous civilizations. The Ute lived across both Western Colorado and the eastern high plains. The Anasazi lived in the southwestern, southern, and parts of southeastern Colorado. The Comanche and Jicarilla Apache lived in the area that would become the southeastern portions of the Territory. The Arapaho and Cheyenne also had a presence in the eastern and northeastern plains of the area at times.

The earliest explorers of European extraction to visit the area were Spanish explorers such as Coronado, although the Coronado expedition of 1540–42 only skirted the future border of the Colorado Territory to the south and southeast. In 1776, Francisco Atanasio Domínguez and Silvestre Vélez de Escalante explored southern Colorado in the Dominguez-Escalante Expedition.

Other notable explorations included the Pike Expedition of 1806–07 by Zebulon Pike, the journey along the north bank of the Platte River in 1820 by Stephen H. Long to what came to be called Longs Peak, the John C. Frémont expedition in 1845–46, and the Powell Geographic Expedition of 1869 by John Wesley Powell.

In 1779, Governor de Anza of New Mexico fought and defeated the Comanches under Cuerno Verde on the Eastern Slope of Colorado, probably south of Pueblo. In 1786, de Anza made peace with the Comanches, creating an alliance against the Apaches.

A group of Cherokee crossed the South Platte and Cache la Poudre River valleys on their way to California in 1848 during the California Gold Rush. They reported finding trace amounts of gold in the South Platte and its tributaries as they passed along the mountains. In the south, in the San Luis Valley, early Mexican families established themselves in large land grants (later contested by the U.S.) from the Mexican government.

In the early 19th century, the upper South Platte River valley had been infiltrated by fur traders, but had not been the site of permanent settlement. The first movement of permanent U.S. settlers in the area began with the Kansas–Nebraska Act of 1854, which allowed private land claims to be filed. Among the first settlers to establish claims were former fur traders who returned to the lands they once trapped, including Antoine Janis and other trappers from Fort Laramie, who established a town near Laporte along the Cache la Poudre in 1858. See Forts in Colorado.

In 1858, Green Russell and a party of Georgians, having heard the story of the gold in the South Platte from Cherokee after they returned from California, set out to mine the area they described. That summer they founded a mining camp Auraria (named for a gold mining camp in Georgia) at the confluence of the South Platte and Cherry Creek. The Georgians left for their home state the following winter. At Bent's Fort along the Arkansas River, Russell told William Larimer, Jr., a Kansas land speculator, about the placer gold they had found. Larimer, realizing the opportunity to capitalize on it, hurried to Auraria. In November 1858, he laid claim to an area across Cherry Creek from Auraria and named it "Denver City" in honor of James W. Denver, the previous governor of the Kansas Territory. Larimer did not intend to mine gold himself; he wanted to promote the new town and sell real estate to eager miners.

Larimer's plan to promote his new town worked almost immediately, and by spring 1859 the western Kansas Territory along the South Platte was swarming with miners digging in river bottoms in what became known as the Colorado Gold Rush. Early arrivals moved upstream into the mountains quickly, seeking the lode source of the placer gold, and founded mining camps at Black Hawk and Central City. A rival group of civic individuals, including William A.H. Loveland, established the town of Golden City at the base of the mountains west of Denver City, with the intention of supplying the increasing tide of miners with necessary goods.

The movement to create a territory within the present boundaries of Colorado followed nearly immediately. Citizens of Denver City and Golden City pushed for territorial status of the newly settled region within a year of the founding of the towns. The movement was promoted by William Byers, publisher of the Rocky Mountain News, and by Larimer, who aspired to be the first territorial governor. In 1859, settlers established the Territory of Jefferson, and held elections, but the United States Congress did not recognize the territory, and it never gained legal status.

Congressional grant of territorial status for the region was delayed by the slavery issue, and a deadlock between Democrats, who controlled the Senate, and the antislavery Republicans, who gained control of the House of Representatives in 1859. The deadlock was broken only by the Civil War. In early 1861, enough Democratic senators from seceding states resigned from the U.S. Senate to give control of both houses to the Republicans, clearing the way for admission of new territories. Three new territories were created in as many days: Colorado (February 28), Nevada (March 1), and Dakota (March 2).

Colorado Territory was officially organized by Act of Congress on February 28, 1861 (12 Stat. 172), out of lands previously part of the Kansas, Nebraska, Utah, and New Mexico territories. Technically the territory was open to slavery under the Dred Scott Decision of 1857, but the question was rendered moot by the impending American Civil War and the majority pro-Union sentiment in the territory. The name "Colorado" was chosen for the territory. It had been previously suggested in 1850 by Senator Henry S. Foote as a name for a state to have been created out of present-day California south of 35° 45'.

During the Civil War, the tide of new miners into the territory slowed to a trickle, and many left for the East to fight. The Missourians who stayed formed two volunteer regiments, as well as home guard. Although seemingly stationed at the periphery of the war theaters, the Colorado regiments found themselves in a crucial position in 1862 after the Confederate invasion of the New Mexico Territory by General Henry Sibley and a force of Texans. Sibley's New Mexico campaign was intended as a prelude to an invasion of the Colorado Territory northward to Fort Laramie, cutting the supply lines between California and the rest of the Union. The Coloradans, under the command of Union Army General Edward Canby and Colonel John P. Slough, Lt. Col. Samuel F. Tappan and Major John M. Chivington, defeated Sibley's force at the two day Battle of Glorieta Pass along the Santa Fe Trail, thwarting the Confederate strategy.

In 1851, by the Treaty of Fort Laramie, the United States acknowledged the Cheyenne and Arapaho tribes control, in the Colorado area, of the Eastern Plains between North Platte River and Arkansas River eastward from the Rocky Mountains. The Fort Laramie Treaty, in Article 2 of the treaty, did allow the U.S., government to build roads, military and other posts on Indian lands. If these roads could be used by U.S. citizens to lawfully pass through the Indian territories was not stated but apparently implied since the U.S. government bound itself to protect Indian nations against depredations by U.S. citizens. The treaty did not grant any rights for the erection of posts or settlements by U.S. civilians. Since this treaty was enacted before the railroads had come and before the finding of gold in the region, few whites had ventured to settle in what is now Colorado. By the 1860s, as a result of the Colorado Gold Rush and homesteaders encroaching westward into Indian terrain, relations between U.S. and the Native American people deteriorated. On February 18, 1861, in the Treaty of Fort Wise, several chiefs of Cheyenne and Arapaho supposedly agreed with U.S. representatives to cede most of the lands, ten years earlier designated to their tribes, for white settlement, keeping only a fragment of the original reserve, located between Arkansas River and Sand Creek. This new fragment was assigned in severalty to the individual members of the respective tribes with each member receiving 40 acres (160,000 m) of land. The United States, by the Fort Wise Treaty, wished to have the Indians settle the new reservation as farmers. The U.S. agreed to pay the tribes a combined total of $30,000 per year for 15 years and in addition to provide a lumber mill, one or more mechanic shops, dwelling houses for an interpreter, and a miller engineer. See Article 5 of the Fort Wise Treaty.

A good part of their co-nationals repudiated the treaty, declared the chiefs not empowered to sign, or bribed to sign, ignored the agreement, and became even more belligerent over the 'whites' encroaching on their hunting grounds. Tensions mounted when Colorado territorial governor John Evans in 1862 created a home guard of regiments of Colorado Volunteers returning from the Civil War and took a hard line against Indians accused of theft. On August 21, 1864, a band of 30 Indians attacked four members of the Colorado Cavalry as they were rounding up stray cattle. Three of the members made it back to the stockade at Franktown, Colorado, but the fourth man failed to return. This man, Conrad Moschel, was found a few days later having been shot with a firearm and pierced with an arrow, and had been scalped in the manner of the Cheyenne. This offensive action by the warring Cheyenne further enraged the U.S. people of Colorado. After several minor incidents in what would later come to be designated as the Colorado War, in November 1864, a force of 800 troops of the Colorado home guard, after heavy drinking, attacked an encampment of Cheyenne and Arapaho at Sand Creek, murdering between 150 and 200 Indians, mostly elderly men, women and children. This Sand Creek Massacre or 'Massacre of Cheyenne Indians' led to official hearings by the United States Congress Joint Committee on the Conduct of the War in March and April 1865. After the hearings, the Congress Joint Committee in their report on May 4, 1865, described the actions of Colonel John Chivington and his Volunteers as "foul, dastardly, brutal, cowardly" and:

It is difficult to believe that beings in the form of men, and disgracing the uniform of United States soldiers and officers, could commit or countenance the commission of such acts of cruelty and barbarity as are detailed in the testimony, but which your committee will not specify in their report.

Nevertheless, justice was never served on those responsible for the massacre; and nonetheless, the continuation of this Colorado War led to expulsion of the last Arapaho, Cheyenne, Kiowa and Comanche from the Colorado Territory into Oklahoma.

Following the end of the American Civil War, a movement was made for statehood; the United States Congress passed the Admission Act for the territory in late 1865, but it was vetoed by President Andrew Johnson. For the next eleven years, the movement for territorial admission was stalled, with several close calls. President Grant advocated statehood for the territory in 1870, but Congress did not act.

In the meantime, the territory found itself threatened by lack of railroads. By the late 1860s, many in Denver had sold their businesses and moved northward to the Dakota Territory communities of Laramie and Cheyenne, which had sprung up along the transcontinental railroad. Faced with the possible dwindling of the town and its eclipse by the new towns to the north, Denverites pooled their capital and built the Denver Pacific Railroad northward to Cheyenne to bring the rail network to Denver. The Kansas Pacific Railway was completed to Denver two months later. The move cemented the role of Denver as the future regional metropolis. The territory was finally admitted to the Union in 1876.

Three Colorado cities served as the capital of the Territory of Colorado:

1. Denver City: from creation on February 28, 1861, until July 7, 1862.
2. Colorado City: July 7 until August 14, 1862.
3. Golden City: August 14, 1862 until December 9, 1867.
4. Denver: December 9, 1867 until statehood on August 1, 1876.

For much if not all of its existence, the Colorado Territorial government did not actually own its houses of government, instead renting available buildings for governmental purposes. Today, two buildings which served the Territorial government remain: the historic log building in Colorado City, and the Loveland Block in downtown Golden City (which had housed the complete legislature, Territorial Library and possibly Supreme Court from 1866 to 1867, with library remaining to 1868). Others which served include the original Loveland Building (1859–1933, 1107 Washington Avenue in Golden, housing the Territorial House from 1862 to 1866); the Overland Hotel (1859–1910, 1117 Washington Avenue in Golden, housing the Territorial Council from 1862 to 1866); and the Territorial Executive Building (unknown dates, approximately 14th and Arapahoe Streets in Golden, housing the executive branch of the government from 1866 to 1867).

• Colorado in the American Civil War
• Colorado War
• Comanche Campaign
• List of governors of the Territory of Colorado
• List of territorial claims and designations in Colorado
• Pike's Peak Country
• Pike's Peak Gold Rush
• Territory of Jefferson
• Bibliography of Colorado
• Geography of Colorado
• History of Colorado
• Index of Colorado-related articles
• List of Colorado-related lists
• Outline of Colorado

• Hawes, J. W. (1879). "Colorado, a territory of the United States" . The American Cyclopædia.

38°59′50″N 105°32′52″W / 38.9972°N 105.5478°W / 38.9972; -105.5478 (Territory of Colorado (historical))