The Centennial State has 697 sides‚ not four.
- Colorado looks like a rectangle. It isn’t.
- The Centennial State has not four, but 697 sides. That makes it a hexahectaenneacontakaiheptagon.
- Does that make Wyoming the only real rectangular state? Well, about that…
America loves its straight-line borders. The only U.S. state without one is Hawaii – for obvious reasons (1).
West of the Mississippi, states are bigger, emptier and boxier than back East. From a distance, all seem to be made up of straight lines.
Only when you zoom in do you see their squiggly bits: the northeast corner of Kansas, for instance. Or Montana’s western border with Idaho that looks like a human face. Or Oklahoma’s southern border with Texas, meandering as it follows the Red River.
New Mexico comes tantalisingly close to having only straight-line borders. There’s that short stretch north of El Paso that would have been just 15 miles (24 km) long if it was straight instead of wavy.
No, there are only three states whose borders are entirely made up of straight lines: Utah, which would have been a rectangle if Wyoming hadn’t bitten a chunk out of its northeastern corner; Wyoming itself; plus Colorado.
Red: states with only straight-line borders. Yellow: states with some straight-line borders. Green: states without straight-line borders. Image: mapchart.net
Except that they aren’t. For two distinct reasons: because the earth is round, and because those 19th-century surveyors laying out state borders made mistakes.
Congress defined the borders of Colorado as a geospherical rectangle, stretching from 37°N to 41°N latitude, and from 25°W to 32°W longitude (2). While lines of latitude run in parallel circles that don’t meet, lines of longitude converge at the poles.
Which means that Colorado’s longitudinal borders are slightly further apart in the south. So if you’d look closely enough, the state resembles an isosceles trapezoid (3) rather than a rectangle. Consequently, the state’s northern borderline is about 22 miles (35 km) shorter than its southern one. The same goes, mutatis mutandis, for Wyoming.
That’s not where the story ends. There’s boundary delimitation: the theoretical description of a border, as described above. But what’s more relevant is boundary demarcation: surveying and marking out the border on the ground. Colorado entered the Union in 1876.
Only in 1879 did the first boundary survey team get around to translating Congress’s abstract into actual boundary markers. The official border would not be the delimited one, but the demarcated one. Unfortunately, 19th-century surveyors lacked satellites and other high-precision measurement tools.
Let’s not be too harsh: considering the size of the task and the limitation of their tools — magnetic compasses and metal chains — they did an incredible job. They had to stake straight lines irrespective of terrain, often through inhospitable land.
But yes, errors were made — and were in fact quite habitual. Take for example the 49th parallel, which for more than 1,200 miles forms the international border between the U.S. and Canada. Rather than being a straight line, it zigzags between the 912 boundary monuments established by successive teams of surveyors (the last ones in 1872–4). The markers deviate by as much as 575 feet north and 784 feet south of the actual parallel line.
Colorado, not as rectangular as you think. Image: FascinatingMaps.com
The same kind of thing happened when the first surveying teams went out to demarcate the Colorado border. This map magnifies four of the most egregious surveying inaccuracies, where the difference between the boundaries delineated by Congress and the border demarcated by the surveyors is greatest.
Four Corners (and four more)
Four Corners. Clockwise from top left: Utah, Colorado, New Mexico, Arizona. Image source: Getty Creative
Located in a dusty, desolate corner of the desert, the Four Corners monument seems very far from the middle of anything. Yet this is the meeting point of four states: Utah, Colorado, New Mexico and Arizona. It is the only quadripoint in the United States (4). The monument’s exact location is at 36°59’56″N, 109°02’43″W.
However, it’s not where Congress had decreed the four states to meet. That point is about 560 feet (170 m) northwest of the quadripoint’s current location, at 37°N, 109°02’48″W. Did you drive all the way through the desert to miss the actual point by a few hundred feet?
No, you didn’t: in 1925, the Supreme Court ruled that the borders as surveyed were the correct ones. But perhaps the original quadripoint deserves a small marker of its own, if only to provide the site with an extra attraction. Or why not go for three? Some sources say the original point deviates by 1,807 feet (551 m).
(For more on this, and other interesting articles, please visit: https://bigthink.com/strange-maps/colorado-is-not-a-rectangle/)