Submitted by GreenKeel t3_yccayd in explainlikeimfive
Red_AtNight t1_itlm6ch wrote
There have been a couple of different survey systems over the years. A lot of Western North America was laid out using what are called Survey Townships - basically, you make a square that is 6 miles long by 6 miles wide. That gives you 36 square miles. An area of 1 square mile is called a "Section," so within a survey township you have 36 sections. Sections could be further subdivided into quarter-sections (160 acres,) or even smaller units at will. This is also why if you look at the map of counties in most states west of the Mississippi, most of the counties are squares.
How did you know the boundaries? The General Land Office, which was an office of the US Government during the time of westward expansion, hired surveyors to mark out the boundaries. They would literally hammer large spikes into the ground at the corners of properties.
In fact, to this day, you can often see property stakes. Nowadays they're more likely to be made of wood, but some of the old iron pins are still out there.
a_bear_there_was t1_itmirwt wrote
Many markers are still metal. Wooden stakes may be used for temporary markings, but the actual reference points those are based on will be designed to be permanent.
You can probably find a variety of survey markers in the pavement in your neighborhood, if you know what to look for. For minor locations, they're usually a small pin driven into the concrete or asphalt.
For more major stations, they'll have a circular disk with information about the station. Even more rarely, you'll find geodetic survey markers that contain information about the actual curvature of the Earth at that point, since even the shape of the Earth can vary enough to be significant at large scales.
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