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Measurements in Land Surveying

When reading legal land survey descriptions there are several things a land surveyor must keep in mind to conduct a proper survey. For example, the following legal description is for a 42- acre parcel – T39N, R23W, Sec. 4, NW1/4 SE1/4.

First, one must understand that punctuation is crucial in reading legal land surveys.  If a comma were included in between the “NW1/4” and “SE1/4” of this legal measurement/description then it would alter the reading to be for a 320 acre parcel.  Second, all legal descriptions are read backwards.  The legal land survey description is read from right to left, going from the smallest unit of measurement to the largest unit of measurement.  Understanding these key points will enable you to conduct a more precise and accurate survey.


The Rectangular Survey System

Land surveying consists largely of determining the measurements of parcels of land.  The Rectangular Survey System or the Public Land Survey System (PLSS) is the primary type of land survey measurement system that the majority of the United States has been surveyed by.  It is a system that is setup on a grid in which the primary objective is to determine approximate values of square sections measuring 1 square mile each (1 square mile = 5,280 feet).  The rectangular survey system is the most common system land surveyors use throughout their career to define accurate and precise measurements.

Land Surveying Measurements


In order to apply the rectangular survey system you must first understand a couple terms.  These include prime meridiansbaselines, and principal meridians.  Prime Meridians are north-south lines (lines of longitude), at which longitude is defined to be 0°.  The Prime Meridian starts at the North Pole and extends south to the South Pole.  Baselines are lines that extend east-west.  Principal meridians are the true north-south lines that run through the initial point of the area that is being covered.

Rectangular surveying system and Land Surveying Measurements


All measurement starts at an initial point.  Initial points in land surveying are usually set by astronomical observation.  Across the United States there are 37 points where a principal meridian and baseline intersect.  From each of these initial points, a prime meridian extends north-south, and a baseline extends east-west.  Along the north-south prime meridian, initial points are marked at 24 mile intervals.  Baselines extend from east to west from these points as well.  Along the east-west baselines, points are marked at 24 mile intervals as beginning from the north-south prime meridian.  The parallel points created from these points are called standard corners.

For each standard corner a line runs true north.  These lines are called guide meridians.  Due to the Earth’s curvature, guide meridians do not intersect through standard corners along the next standard parallel, 24 miles to the north.  The intersections they cross are called closing corners.  Each standard now contains a set of both standard and closing corners.

Closing corners and Land Surveying Measurements



Each 24-mile tract is divided up into 16 townships. Townships are roughly 6 miles x 6 miles.  Starting at the southeast corner of the 24-mile tract, corners are established six miles apart along the east-west parallel and the north-south meridians. From these corners, range lines run true north to the next parallel, and township lines run west to the next prime meridian.  With that said, each township is now divided into 36 sections, a piece of land roughly 1 square mile x 1 square mile, or approximately 640 acres.  This process is also used in defining corners and running lines from the southeast corner of the township.  Each of the 36 sections is then divided into 16 forties.  These forties are further subdivided, and subdivided, and subdivided.

Surveying students and Land Surveying Measurements

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