May 6, 2026
Colorado at 150: How the Centennial State Earned Its Name — and Its Borders
On August 1, 1876 — exactly 100 years after the Declaration of Independence — Colorado became the 38th state admitted to the Union. That timing earned it the nickname "The Centennial State," and in 2026, Colorado reaches its own sesquicentennial: 150 years of statehood. Behind the anniversary is a geographic story about mountains, borders, water, and the peculiar decision to draw a state as a near-perfect rectangle.
The Rectangle That Isn't
Colorado looks like a perfect rectangle on a map, and people often call it one of only two rectangular states (along with Wyoming). But it's not actually a rectangle. Colorado has four straight borders defined by lines of latitude and longitude: 37°N on the south, 41°N on the north, 102°04'W on the east, and 109°03'W on the west. On a flat map, those look like right angles. On a sphere, they don't.
Because lines of longitude converge toward the poles, Colorado's northern border is about 21 miles shorter than its southern border. The state is actually a quadrilateral — technically closer to a trapezoid than a rectangle. And if you measure with modern GPS precision, the 19th-century survey markers that define the borders don't line up perfectly with the intended latitude and longitude lines. Colorado has 697 sides, not four, when you account for every surveyed segment. Congress drew a rectangle on paper; reality delivered something more complicated.
A State Split by the Continental Divide
The Rocky Mountains run north-south through the center of Colorado, and with them comes the Continental Divide — the hydrological spine of North America. Rain that falls on the east side of the Divide flows toward the Atlantic (via the South Platte, Arkansas, and Rio Grande rivers). Rain on the west side flows toward the Pacific (via the Colorado River). This single geographic feature creates two fundamentally different Colorados.
The Eastern Plains are part of the Great Plains — flat, dry, agricultural, and sparsely populated. Drive east from Denver and within an hour you're in wheat-and-cattle country that looks more like Kansas than the Colorado of tourist brochures. The Western Slope — everything west of the Divide — is high desert, red rock canyons, and mesa country, with ski towns tucked into the mountain valleys. And the Front Range corridor, where the Rockies meet the Plains, is where 80% of Colorado's population lives: Denver, Colorado Springs, Fort Collins, Boulder. The geography funnels people into a narrow band along the mountain front.
The Highest State
Colorado has the highest mean elevation of any state: approximately 6,800 feet above sea level. It contains 58 peaks above 14,000 feet (known locally as "fourteeners"), more than any other state. Mount Elbert, at 14,440 feet, is the highest point in the entire Rocky Mountain chain. The state's lowest point — where the Arikaree River crosses into Kansas — is still 3,315 feet, higher than the highest point in 18 other states.
This elevation shapes everything. Denver, the "Mile High City," sits at exactly 5,280 feet — a fact literally engraved into the steps of the state capitol. The thin air at altitude means water boils at a lower temperature (about 202°F in Denver, not 212°F), which is why cake mix boxes include high-altitude instructions specifically for Colorado bakers. Athletes train in Colorado to build red blood cell counts. And the UV exposure at altitude is intense — Colorado has some of the highest skin cancer rates in the country despite not being a traditionally "sunny" beach state.
Water Wars: The Colorado River Compact
The state of Colorado gave its name to the Colorado River — and then spent the next century fighting over its water. The Colorado River Compact of 1922 divided the river's flow between seven states (Colorado, Wyoming, Utah, New Mexico in the Upper Basin; Arizona, Nevada, California in the Lower Basin) plus Mexico. The problem: the compact was negotiated during unusually wet years, and it allocated more water than the river actually carries in an average year.
Today, Lake Mead and Lake Powell — the two largest reservoirs in the US, both fed by the Colorado River — have seen dramatic declines. The river that carved the Grand Canyon now barely reaches the sea. For Colorado, water politics are inseparable from geography. The state sits at the headwaters: snow falls in the Rockies, melts into the Colorado River, and flows 1,400 miles to the Gulf of California. Every gallon that Denver uses is a gallon that doesn't reach a farm in Arizona or a faucet in Los Angeles. In the arid West, geography is hydrology, and hydrology is power.
Colorado by the Numbers
A few data points that capture the Centennial State at 150:
- Population: approximately 5.9 million — the 21st most populous state, but one of the fastest-growing over the past two decades.
- Land area: 104,094 square miles — the 8th largest state.
- National parks: 4 — Rocky Mountain, Black Canyon of the Gunnison, Mesa Verde, and Great Sand Dunes. Plus 8 national monuments and multiple NPS sites.
- Lowest obesity rate in the nation: Colorado consistently ranks as the leanest state, with an adult obesity rate near 25% — the altitude and outdoor culture likely both contribute.
- 300+ days of sunshine per year: Despite being a mountain state, Colorado gets more sun than many traditionally sunny states.
Dive deeper into the data on our Colorado Fast Facts page — demographics, agriculture, health, parks, and climate data, all sourced from federal APIs.
The Name Itself
"Colorado" comes from the Spanish word for "colored red" — a reference to the red sandstone and silt of the Colorado River and the dramatic red rock formations found throughout the state's western canyons. Spanish explorers named the river first; the territory, and then the state, took the name from the river. It's one of several US states with Spanish-origin names (along with Montana, Nevada, Florida, and California), a reminder that the American West was Spanish territory long before it was American.
Test Your Colorado Knowledge
Can you spot Colorado on a blank map? Try Just States and find out. Play the GeoProwl daily challenge for data-driven clues that might just be about the Centennial State. Or explore all 50 states on Fast Facts.