South Dakota’s Western Border

If you look at a map of South Dakota, you can see that the western border isn't perfectly straight. Right where Wyoming, Montana, and South Dakota meet, the border jogs inward a little bit.

The story goes (which I've found in several sources) that this isn't how it was supposed to be. The border was supposed to run straight down the 27th meridian, but the surveyors messed up. The lines they ran from north and south didn't meet up properly, and to fix the error they just made the border jog in slightly, as it does, in order to connect the two lines.

Google Maps

You can find the story of the surveying error told in Joey Green's Dumb History. There's also some discussion of the issue over at the Straight Dope message boards.
     Posted By: Alex - Fri Jun 24, 2016
     Category: Geography and Maps

If you look at Google Maps of that area you can see that not only does the border of S Dakota zig a little, so does the southern corner of Montana. It curves slightly ENE and then has an pointed extra eastern projection on the corner.
Posted by Kevin on 06/25/16 at 10:19 PM
Surveying over long distances+boredom+whiskey=you do the math.
Posted by Patty in Ohio, USA on 06/25/16 at 11:45 PM
You'll find a similar jog in Colorado's western border, 25-30 miles SE of Moab, UT, making it a hexagon, not a rectangle.

On a wholly unrelated note (or maybe not), a subdivision in the heart of Minturn, CO, was surveyed about 5 feet out of square. Zoom in close enough on Google maps and it's not hard to see who put their house parallel to Main St., and who oriented on the side streets.
Posted by R'Chard on 06/26/16 at 04:10 PM
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