2026 marks an important milestone for our state. This year is the 150th anniversary of Colorado’s admission to the United States as the 38th state. 

The story of Colorado’s journey to statehood begins in 1803 with the Louisiana Purchase, when Thomas Jefferson, the third president of the newly formed United States, acquired the Louisiana Territory from Napoleon’s French First Republic for approximately $15 million or roughly four cents an acre. The territory consisted of the Mississippi River’s drainage basin west of the river itself, which included the land in what would become Colorado east of the continental divide.  It essentially doubled the size of the United States.

The Western Slope, including what would become Redstone, would remain part of Spain and then Mexico for 45 years following the Louisiana Purchase. In 1846, the United States would pursue a war of expansion against Mexico, kicking off the Mexican-American War. The war would come to a close with Mexico and the United States signing the Treaty of Guadalupe Hidalgo, which ceded to the United States the Mexican territories of Alta California and Santa Fe de Nuevo México, as well as Texas, which had been disputed between the two countries prior. The territory of Santa Fe de Nuevo México included the Western Slope of what would become the state of Colorado, bringing the other half of the future state under United States jurisdiction.

Following the Treaty of Guadalupe Hidalgo, the land that would become Colorado became part of other surrounding territories, including the Kansas, Nebraska, Utah, and New Mexico Territories. In July 1858, gold was found by Euro-American prospectors near Pike’s Peak in what was at that time the western part of the Kansas territory. After news spread of the gold at Pike’s Peak, a gold rush ensued, with a massive influx of Euro-American settlement in the southern Front Range. As with the larger push west of Manifest Destiny, the Pike’s Peak Gold Rush would start the trend in Colorado of Native American displacement by Euro-American settlers looking to exploit the land they had called home for centuries. Specifically, the Cheyenne and Arapahoe would see their land in the Front Range occupied and the former treaty guaranteeing them that land be rewritten, confiscating it from them and giving it to these new settlers. Prior to the Pike’s Peak Gold Rush, the United States government and many Euro-Americans viewed Colorado as an unprofitable wasteland, too mountainous to truly capitalize on, and thus, they were happy to leave it to the Native American tribes that called it home, treating it as another Indian Territory. 

Ambitious Euro-American prospectors took over the Front Range quickly, setting up “boom towns” to accommodate their ventures. It is through this boom town wave that we see many of Colorado’s biggest cities first appear, including Denver and Boulder. The influx of migrants would stoke desires for a territorial government of their own. On February 28, 1861, towards the end of the gold rush hysteria, the Colorado Territory would be formed, with the new territory’s borders being the same as the future state’s borders. 

When people think of Colorado history, they often do not think of the American Civil War. However, the war back east had a great deal of influence on Colorado’s bid for statehood. During the American Civil War, Colorado’s statehood took a backseat as Washington felt it had more pressing issues at hand. The Colorado Territory was aligned with the Union and even sent two territorial regiments of Coloradans to halt a Confederate expeditionary force attempting to traverse the New Mexico Territory. The Colorado regiments confronted and routed the Confederate force at Glorietta Pass east of Santa Fe. 

While the Civil War raged on in the East, the Colorado Territory was waging its own war. The Colorado War lasted from 1864 to 1865 and saw the eastern plains tribes of the Cheyenne and Arapaho form an alliance in an effort to defend against Euro-American encroachments. It was in the midst of this conflict that the infamous Sand Creek Massacre was perpetrated by the 3rd Colorado Cavalry under the command of Colonel John M. Chivington. More than 230 Cheyenne and Arapahoe people were killed and mutilated in the massacre; most of the victims were women, children, and the elderly. Chivington, who had led the attack and John Evans, the territorial governor who supported the massacre, were both proponents of statehood. Chivington hoped to become a representative in the House, and Evans wanted to become a senator for Colorado. However, the two men would face scrutiny for their roles in the Sand Creek Massacre, with Evans being forced to step down as territorial governor. Despite Colorado’s becoming a state, the two men would never achieve the positions they had hoped for due to their unapologetic promotion of and roles in the Sand Creek Massacre. 

After the Civil War, a desire for statehood would reignite in the Colorado Territory. Coloradans voted to pursue statehood in 1865; however, after Colorado statehood passed both chambers of the Republican held Congress, it was vetoed by President Andrew Johnson. Johnson, a Democrat with sympathies for the Confederacy, feared that a Colorado state would mean two new Republican senators.  It is important to remember that the Republican and Democratic parties of the post-Civil War era were very different from the parties we know today, with different ideologies and platforms. 

Johnson justified his veto by citing that statehood was not unanimously popular in Colorado, and the territory did not yet have the population necessary for statehood. Both these points were disputed by Republicans, both in Congress and in Colorado. An example of the disagreement with statehood came when 600 miners in Colorado signed a pledge promising potential tax collectors from a new state “bullets instead of dollars.” Many Coloradans enjoyed the territorial status, as it meant they only had to pay federal taxes. While some Coloradans objected to statehood, many others were excited at the prospect, as it would mean more autonomy and representation in the federal government. It would also allow for more local administration. 

Johnson would leave office in 1869, and Ulysses S. Grant would become President. Grant, being a Republican, looked more favorably on Colorado statehood. However, Colorado’s several statehood attempts early in the Grant administration would fail to pass both houses of Congress. This was because now that Republicans held the presidency and both Houses of Congress, there was less fervor to add new Republican states and senators. The tide would change when Jerome Chaffee, who would soon become one of the first senators for Colorado, convinced Congress that Colorado would reach the population requirement by 1875.