About
Colorado

Every schoolchild in America learns that two states are rectangles: Colorado and Wyoming. It is one of those facts that feels too simple to be wrong.

It is wrong twice over.

Problem one: the Earth is round

Congress defined Colorado using lines of latitude and longitude — 37°N to 41°N, and 25°W to 32°W measured from Washington rather than Greenwich, which is how boundaries were written at the time.

That sounds like a rectangle. It is not, because lines of latitude run parallel and lines of longitude converge toward the poles. The eastern and western borders of Colorado are therefore slightly further apart in the south than in the north.

The practical consequence: Colorado's northern border is roughly 22 miles shorter than its southern border. Even in pure theory, before anyone picked up a surveying chain, the state was an isosceles trapezoid rather than a rectangle. The same is true of Wyoming.

Twenty-two miles is not a rounding error. It is the distance from downtown Denver to Boulder.

Problem two: the men with the chains

This is where it gets genuinely interesting, because there is a difference between two things that sound identical.

Delimitation is the description of a border — the words Congress writes down. Demarcation is going out into the physical world and putting stakes and stone cairns in the dirt to say here.

The official border is the demarcated one. Whatever the surveyors actually marked is what counts, not what Congress meant.

Colorado entered the Union in 1876. The first boundary survey team did not get around to translating that description into markers until 1879. Consider what those men were doing. No satellites. No GPS. Magnetic compasses and metal chains, walking a straight line across mountains, deserts and canyons, driving a marker every mile, in country with no roads.

They did remarkable work. They also made mistakes, constantly.

The Utah–Colorado survey is the clearest example. A single party started at the Four Corners in 1879 and marched north along what was supposed to be a fixed meridian, placing a marker each mile. When they reached the Wyoming line, they were not where they expected to be. Somewhere in that long walk, the line had jogged west. Later surveys in 1885 and 1893 found the errors — but by then the boundary was legally fixed at the original markers, and moving it would have required agreement from both states plus an act of Congress.

Nobody was going to do that. So the mistakes became the border.

The four big wobbles

Most of the 697 sides are tiny — a few dozen feet here, a hundred there. But there are several deviations big enough to see on a map if you know where to look.

The largest is on the western border, between the country near La Sal, Utah, and Montrose County near Paradox, Colorado. Over an eight-mile stretch, the survey team angled westward by more than a mile.

On the southern border with New Mexico there is a section known as the Edith Deviation, where the line bends to follow a small valley running northwest to southeast. That one may not be an error at all — it looks like the surveyors, for once, simply gave in to the terrain and followed the ground rather than fighting it.

And then there is the Oklahoma stretch. In the final 53 miles before the border turns north, along the flattest, most featureless country in the entire survey, the line swerves south by as much as 1,770 feet. There is no terrain to blame. The best guess anyone has offered is that the surveyors were confused by how completely featureless the place was.

The Supreme Court makes it permanent

Errors on the southern border with New Mexico eventually produced lawsuits, and those lawsuits climbed all the way to the U.S. Supreme Court.

In 1925 the Court ruled that the surveyed line was the real line. The mistakes were the border. They were not going to be corrected, then or ever.

That single decision is why the shape is permanent. Modern GPS can show you precisely where the mathematical border should be, down to the centimetre. It does not matter. The legal boundary is a set of nineteenth-century stone piles, and the law says the stone piles win.

The Four Corners is also in the wrong place

The most-photographed consequence of all this is the Four Corners Monument, the only point in the United States where four states meet.

It is not at the mathematically correct spot. The marker sits roughly 1,800 feet from where the meridian and parallel actually intersect.

People periodically discover this and get indignant about it, usually after driving several hours to stand on it. The courts have repeatedly and consistently ruled the same way they did in 1925: the surveyor's mark is the boundary. The monument is exactly where the corner legally is, because the corner is defined as being wherever the surveyor said it was.

Which is, if you think about it, a more honest way to run a country than pretending the map was ever perfect.

Why this is the best fact about Colorado

I like this story more than any other piece of Colorado trivia, and not because it is quirky.

It is the whole state in miniature. Colorado looks orderly from a distance — a clean box on a map, a tidy grid of counties, a rational plan. Get closer and it is all improvisation: people doing difficult work with inadequate tools in unforgiving country, making errors that then became permanent because undoing them was harder than living with them.

That describes the mining towns, the water law, the highway system and most of the ski industry too.

The state has 697 sides because a few dozen men walked across mountains and deserts with a compass and a chain and got it almost right. Almost right, permanently, is a very Colorado outcome.

And the word for a 697-sided polygon — hexahectaenneacontakaiheptagon — is real, is nearly unpronounceable, and is the single best thing you can drop into a conversation at a bar in this state.

Sources: U.S. Supreme Court boundary rulings (1925); Bureau of Land Management survey records; Denver Public Library Western History Collection; OpenStreetMap boundary data. The 697 figure counts distinct straight-line segments in the surveyed boundary.

Most states pick their symbols the way you would expect: a legislator introduces a bill, a lobby group backs it, it passes on a voice vote and nobody thinks about it again.

Colorado does something stranger. A striking share of this state's official emblems exist because a classroom decided they should, and then did the work.

1899: the schoolchildren's vote

The white and lavender columbine — Aquilegia caerulea — was first collected on Pikes Peak in 1820. By the end of the century it was the obvious candidate for state flower, and in 1899 the legislature made it official after Colorado's schoolchildren voted for it.

The columbine came with an unusual legal afterthought. It is protected: picking one on public land is against state law. Colorado decided its flower was worth a statute, which is not something most states bother with.

It is also the marker for every scenic byway in the state. That blue columbine logo on the highway signs is a direct descendant of a nineteenth-century schoolroom ballot.

1982: the fourth graders and the Stegosaurus

This is the best one.

The very first Stegosaurus fossil ever identified was found in Colorado in 1876 — the same year the state entered the Union. Which is a coincidence so tidy it sounds made up.

Nearly a century later, a class of fourth graders decided the state ought to acknowledge it. They ran a letter-writing campaign to the legislature. It took two years. In 1982 the Stegosaurus became Colorado's official state fossil.

Two years is a long time for nine-year-olds to stay on a single lobbying effort. Most adult advocacy campaigns do not last that long.

2012: the salamander

Students from several schools partnered up to convince the governor to designate a state amphibian. In March 2012 the western tiger salamander got the nod.

It was a good pick on the merits, which is worth noting — this was not a sentimental designation. The western tiger salamander is found in all 64 Colorado counties, plains to mountains, which almost nothing else in the state can claim. It is also the largest terrestrial salamander in the world.

The kids chose an animal that genuinely represents the whole state rather than just the photogenic part of it. That is better reasoning than most symbol selection gets.

2014: Girl Scout Troop 2518

Colorado has a state cactus, which surprises people who think of it as a mountain state.

The claret cup — a low, clumping cactus with brilliant scarlet flowers — became the official state cactus in 2014 thanks to Girl Scout Troop 2518 out of Castle Rock.

Again, the pick is smarter than it looks. Naming a cactus is a quiet insistence that Colorado is not only the Rockies. It is also high desert, canyon country and shortgrass prairie, and the claret cup grows in exactly the parts of the state that tourism brochures skip.

The rest of the list, and why it is a decent portrait

Taken together, Colorado's symbols do something most states' lists do not: they cover the actual state rather than the postcard.

• Blue grama grass, adopted 1897 — a prairie grass whose dense roots hold the eastern plains soil in place. The oldest symbol on the list, and it is about the plains.
• Lark bunting, 1931 — a grassland bird, not a mountain one.
• Rocky Mountain bighorn sheep — the alpine counterweight.
• Greenback cutthroat trout, 1994 — once believed extinct, later rediscovered. A symbol that is also a conservation story.
• Colorado hairstreak butterfly, 1996 — purple wings edged in orange, living in scrub oak nobody photographs.
• Aquamarine, 1971 — found near the summit of Mount Antero, at 14,000 feet. Colorado's gemstone requires a mountaineering trip to collect.
• Rhodochrosite — the state mineral, a deep rose-red crystal that came out of Colorado mines and is now in museums worldwide.
• Yule marble — the state rock, quarried only near the town of Marble. It went into the first state museum building, and the same quarry supplied the marble for the Lincoln Memorial and the Tomb of the Unknown Soldier.
• Colorado blue spruce — the state tree, first identified on Pikes Peak in 1862.
• Shelter dogs and cats — the state pets are, by statute, animals adopted from Colorado shelters and rescues. Not a breed. A choice.

There is also a state folk dance (square dance, 1992), a state tartan adopted in 1997, a state summer heritage sport that is pack burro racing, and two state songs rather than one — the traditional "Where the Columbines Grow" and, added later, John Denver's "Rocky Mountain High."

Pack burro racing deserves a sentence of its own. Competitors run mountain courses leading a burro carrying a prospector's pack. It descends from mining history and it is the only sport of its kind in the country. Colorado made it an official heritage sport, which is a genuinely eccentric thing for a legislature to do and entirely in character.

The motto is the odd one out

The state seal, adopted in 1877, carries the motto Nil Sine Numine — "nothing without providence."

It is the only symbol on this list that no child had a hand in, and it is the only one that sounds like it was written by a committee of nineteenth-century men in a room. Which it was.

Everything else on the list — the flower, the fossil, the cactus, the salamander — came from people young enough that nobody was obligated to listen to them. They asked anyway, and the state said yes.

That is a better civics lesson than the motto.

Sources: Colorado General Assembly, Colorado Symbols and Emblems; Colorado State Archives; Colorado Virtual Library. Adoption years as recorded by the legislature.

People arrive in Colorado expecting mountains and are surprised by how much of the state is not mountains. The eastern third is flat enough to see the curve of the horizon. The western edge is red rock desert that looks like Utah, because geologically it is Utah.

Here is the actual structure, and why it produces the state's two defining constraints: thin air and scarce water.

The floor is high

Start with the single most important number. Colorado's lowest point is 3,315 feet, on the Arikaree River where it crosses into Kansas.

That is higher than the highest point in twenty other states.

Colorado is the only state entirely above 3,300 feet, and its mean elevation of roughly 6,800 feet is the highest in the country. There is no low ground here. Even the "flat" part of Colorado sits a mile up.

This is why the eastern plains are not like Kansas despite looking like Kansas. They are high plains — drier, colder at night, with more intense sun and a shorter growing season. Denver, at 5,280 feet, is not a mountain city. It sits on the plains, at the point where the plains stop.

The Divide decides everything

The Continental Divide runs the length of Colorado, roughly north to south, wandering along the crest of the Rockies.

Its job is simple and absolute. Rain falling on the west side eventually reaches the Pacific. Rain falling on the east side eventually reaches the Atlantic via the Gulf of Mexico. There is a line on the ground where those two futures are inches apart.

You can stand on it at Milner Pass on Trail Ridge Road, at Loveland Pass, at Independence Pass and at a dozen other places, and the sign will tell you which way the water goes.

The Divide also does something less obvious. It is a weather wall. Storms coming from the west drop their moisture climbing the western slopes and arrive on the eastern side wrung out. That is why the Western Slope gets the powder and the Front Range gets the sunshine, and why the two halves of Colorado have genuinely different climates.

Colorado is a headwaters state

This is the fact that explains most of Colorado's politics.

No major river flows into Colorado. They all start here and flow out. The Colorado, the Rio Grande, the Arkansas, the South Platte, the North Platte — every one of them begins as snow on a Colorado mountain.

The Colorado River rises in Rocky Mountain National Park. By the time it is finished it has supplied Las Vegas, Phoenix, Los Angeles, San Diego and the farmland of the Imperial Valley, and in most modern years it no longer reaches the sea.

The 1922 Colorado River Compact divided that water among seven states using flow measurements taken during an unusually wet stretch of years. The river has been over-allocated on paper for most of a century as a result. Every water fight in the American West is, in some sense, an argument with that document.

Which is why a bad snow year in Colorado is national news. The state finished the 2025–26 winter with snowpack around 61% of median — the lowest in the modern telemetry record — and the consequences ran from closed boat ramps in Summit County to reservoir operations a thousand miles downstream.

Coloradans watch the SNOTEL numbers the way other people watch a stock ticker, and this is why.

The five landscapes

The Great Plains

The eastern third. Shortgrass prairie, dryland farming, irrigated corn along the river valleys, and enormous sky. Pawnee National Grassland and the Comanche National Grassland are here, along with the largest dinosaur tracksite in North America at Picketwire Canyonlands. Almost nobody visits. It is the emptiest and quietest part of the state.

The Front Range

The narrow strip where the plains hit the mountains, running from Fort Collins through Boulder and Denver to Colorado Springs and Pueblo. Roughly four-fifths of Colorado's population lives here, in maybe a tenth of its area. Everything is thirty minutes from a trailhead and four hours from anything genuinely remote.

The Rocky Mountains

The middle. Multiple distinct ranges — the Front Range, Sawatch, Elk, Sangre de Cristo, San Juan, Gore, Mosquito and more — not one continuous wall. All 58 fourteeners are here, plus roughly 647 peaks above 13,000 feet. The Sawatch Range holds both Mount Elbert at 14,440 feet and Mount Massive at 14,428, the two highest points in the entire Rocky Mountain chain.

The Colorado Plateau

West of the Divide, past the mountains. Red rock, deep canyons, mesas and desert. Colorado National Monument, the Black Canyon of the Gunnison, Dinosaur National Monument and the Ancestral Puebloan sites around Mesa Verde. Warmer, drier and several weeks ahead of the mountains in spring.

The intermountain basins

High flat valleys entirely surrounded by peaks. The San Luis Valley is the biggest — a basin at roughly 7,500 feet, ringed by fourteeners, holding the Great Sand Dunes and some of the darkest night skies in the lower 48. North Park, Middle Park and South Park are the others. They are strange places: flat, cold, enormous, and nothing like the mountains that enclose them.

Thin air is not a metaphor

The percentage of oxygen in the air is the same everywhere — about 20.9%. What changes with elevation is pressure, and pressure is what pushes oxygen into your blood.

At Denver's 5,280 feet, air delivers roughly 82% of the oxygen it does at sea level. At 10,000 feet, about 69%. On top of Mount Elbert, about 58%.

This governs more than hiking. It changes how long food takes to cook, how engines perform, how quickly you dehydrate, how alcohol hits, how much sunscreen you need — ultraviolet radiation increases roughly four to five percent per thousand feet — and how well you sleep the first night.

We built a working calculator for this on the reading a mountain day guide, along with the two o'clock thunderstorm rule that comes with living under this much sky.

Why the state is shaped like an argument

Put those pieces together and modern Colorado makes sense.

The water starts in the mountains where almost nobody lives. It is used by the Front Range cities where almost everybody lives, and by farms on the eastern plains, and by six other states downstream. The mountains, which produce the water, hold the least political power. The cities, which consume it, hold the most.

Add a warming climate and a century-old compact based on optimistic measurements, and you have the defining Colorado problem. Not tourism, not growth, not traffic on I-70.

Water. It always comes back to water.

Sources: U.S. Geological Survey; USDA Natural Resources Conservation Service; Colorado Geological Survey; National Park Service; Colorado Division of Water Resources. Elevation figures are USGS published values.

Colorado's place names come from four sources that did not consult each other: Spanish colonial expeditions, Ute and other Indigenous languages, French fur trappers, and mining-camp founders naming things after themselves and their wives.

Then a century of English speakers sanded the edges off all of it.

The result is a state where the pronunciation you would guess from the spelling is frequently wrong, and where correcting a local on the "real" Spanish pronunciation will get you a very specific look.

The ones that catch everybody

Why the Spanish names got anglicised

The San Luis Valley holds the oldest continuously settled towns in Colorado. San Luis was founded in 1851, twenty-five years before statehood, by Hispano settlers moving north from New Mexico. Spanish was the working language of southern Colorado before English was.

Then the mining boom brought a hundred thousand English speakers in a few years, and they did what English speakers do with unfamiliar words: they made them easier to say.

Saguache is the clearest case. It comes from a Ute word, was written down in Spanish orthography, and is now pronounced suh-WATCH by everyone including the people who live there.

There is a real tension in this. In the San Luis Valley and around Trinidad, plenty of families have spoken Spanish continuously for a hundred and seventy years and pronounce these names the way their grandparents did. The anglicised version is not more correct — it is just more common statewide. Use whichever the people around you are using.

The vocabulary

Beyond place names, Colorado has working vocabulary that will not make sense on arrival.

• The Divide — the Continental Divide, always. Not a metaphor.
• The Front Range — both the mountain range and the urban corridor beneath it. Context tells you which.
• The Slope — the Western Slope, everything west of the Divide. A distinct place with distinct politics.
• A 14er — a peak above 14,000 feet, pronounced "fourteener." A 13er is the same idea, and increasingly where experienced people actually go.
• Mud season — the two shoulder periods when mountain towns empty out. April to mid-May, and mid-October to late November.
• Champagne powder — very dry, low-density snow. Steamboat trademarked the phrase, which locals find funny.
• A chinook — a warm downslope wind that can raise Front Range temperatures dramatically in an hour. It is why January in Denver can hit 70°F.
• Bomb cyclone — a rapidly deepening low-pressure system. Colorado gets one or two a year and they close I-70 and the airport.
• Thundersnow — exactly what it sounds like. Rare, alarming, real.
• Green chile — the Colorado version is pork-based and thinner than New Mexico's, and gets poured over almost anything. Ordering it is not optional.
• Chain law — CDOT's traction restrictions during winter storms. Ignoring it is expensive.
• LoDo, RiNo, LoHi — Lower Downtown, River North, Lower Highlands. Denver neighbourhoods, and yes, everyone finds the naming convention slightly embarrassing.
• The 16th Street Mall — the pedestrian corridor through downtown Denver. Locals just say "16th Street."
• Bustang — CDOT's intercity bus service. Genuinely useful and almost nobody outside the state has heard of it.

Two names with history behind them

Mount Blue Sky. Renamed in 2023 from Mount Evans. John Evans was the territorial governor at the time of the Sand Creek Massacre in 1864, and a university-commissioned review found he bore significant responsibility for the conditions that led to it. The new name comes from the Cheyenne people, who are known as the Blue Sky People. If you see the old name on a map or a guidebook, that is why it is different now.

Colorado itself. The name is Spanish for "coloured red" or "ruddy," originally applied to the Colorado River for the red silt it carried. The state was named after the river, not the other way round — and the stretch of river that gave it the name is mostly in Utah and Arizona. Colorado is named after the colour of mud in another state.

Which, after the 697-sided border and a state fossil lobbied for by fourth graders, feels about right.

One rule that covers all of it

If you are not sure how to say something, say it the way the person you are talking to just said it.

Nobody in this state will correct you. Coloradans are, on the whole, not precious about this — a very large share of the population moved here from somewhere else, and everybody mispronounced something in their first month. But people do notice, and matching the local usage is a small courtesy that costs nothing.

Except Buena Vista. If you say BWAY-na in Chaffee County, someone will smile at you, and they will not explain why.

Sources: Colorado State Archives place-name records; U.S. Board on Geographic Names; History Colorado. Pronunciations reflect common local usage, which in several cases differs from the language of origin.