If you take a look at The Centennial State on any map, you see a perfect rectangle in most cases. But the truth is quite far from that.
Colorado is not a rectangle, it’s not even a quadrilateral (or quadrangle). The reason for this surprising fact is that it has many minor deviations along its borders. In this article, we’ll take a look at these deviations and we’ll also dig deeper and find out why they exist.
Below you can see a map which we made to highlight the most noticeable of the state’s border deviations. (Click on the map to view in full size!)
Map legend:
The cause: Surveying errors
On paper, Colorado is one of the only three U.S. states (along with Wyoming and Utah) which use latitude and longitude lines as borders. The state was originally defined by an act of Congress as a geospherical rectangle. The act specified it to stretch from 37°N to 41°N latitude and from 102°2’48″W to 109°02’48″W longitude (25°W to 32°W from the Washington Meridian).
However, the borders didn’t really end up that way. When surveyors set out to define the actual border with boundary markers, they made several mistakes. This happened in the late 19th century when there were no GPS devices or any other precise tools. Also, the terrain that they had to hike through was quite mountainous so these inaccuracies are really not that surprising.
The map above magnifies the four border sections where the legal border is most noticeably different from the latitudes/longitudes defined by Congress.
The most interesting one perhaps is the famous Four Corners Monument. It’s the only location in the United States where four states meet. Its coordinates are 36°59’56″N, 109°02’43″W. We found it to be about 560 feet (170 m) southeast of the congressionally defined location of 37°N, 109°02’48″W. Some news outlets report that it is misplaced by as much as 2000 feet, which we found to be incorrect.
In the early 20th century, when it became clear that the borders are way off at some points, the Supreme Court had to get involved as well. In 1925 the Court ruled that the legal borders are to remain the ones that were defined by the early surveyors. This put an end to the issue and the borders are still the ‘inaccurate’ ones today.
So how many sides does Colorado have?
Due to the surveying errors and their corrections, Colorado is technically a concave polygon which has hundreds of sides and edges. The below map shows all of the vertices on its border:
According to our calculations performed in QGIS based on the outline of the state from OpenStreetMap, Colorado actually has 697 sides (edges). This means it is not a rectangle, it’s a hexahectaenneacontakaiheptagon based on the naming system of polygons by Kutztown University.
| 600 | 90 | and | 7 | gon |
| hexa+hecta | enneaconta | kai | hepta | gon |
Sources:
1: Map of U.S. with Colorado highlighted is from Wikipedia user TUBS.
2: Wikipedia: Colorado, Geography of Colorado, Four Corners Monument
3: Calculations were made with QGIS and Coordinate Distance Calculator
4: The map showing the deviations is based on data from OSM (© OpenStreetMap contributors). + the Keene Uni Polyline Tool.