Survey System
Township and Range Survey System Basics
Whether the rectangular survey applies at all depends on the jurisdiction. States along the eastern seaboard and a few others were never surveyed this way and rely on metes and bounds or plats. Your state portion will test the method your state actually uses.
Three methods describe land in the United States: metes and bounds, recorded plat, and the rectangular survey. The rectangular survey is the grid method, adopted for federal public lands, and it governs descriptions across most of the interior and western states.
Licensing exams lean on it for two reasons. The vocabulary is precise, and the arithmetic is self-contained: a description that looks intimidating resolves into a single acreage figure once you know the order of operations.
How the Grid Is Constructed
The system starts with a pair of reference lines. A principal meridian runs north and south; a baseline crosses it running east and west. Each survey area has its own named pair, and a legal description is meaningless without knowing which principal meridian governs it. That is why a full description names one.
From those references the surveyor lays out two families of lines. Range lines run north and south, creating columns counted east or west of the principal meridian. Township lines run east and west, creating tiers counted north or south of the baseline. A column and a tier intersect to define one township: a square measuring six miles on each side, thirty-six square miles in area.
Each township is subdivided into thirty-six sections, each one mile square. Section numbering follows a fixed serpentine path: it begins in the northeast corner, runs west along the top tier, drops down, reverses to the east, and continues alternating to the end. The result is fixed everywhere the system is used, so the northwest corner is always section six and the southeast corner is always section thirty-six.
One complication is geometric rather than legal. Meridians converge as they approach the pole, so a grid of perfect squares cannot be maintained across large distances. Surveyors inserted correction lines and guide meridians at regular intervals to restart the grid, which produces townships and sections that are slightly under or over the nominal size. Land along those seams is often described as government lots with individually surveyed acreage instead of clean fractions.
Units and Conversions Worth Knowing Cold
Rectangular survey math is division, not formulas. Memorize this short list and most items reduce to arithmetic you can do on scratch paper.
A township measures six miles by six miles, which is thirty-six square miles of area.
A township contains thirty-six sections, and each section is one square mile.
A section contains 640 acres. That figure anchors every other calculation on the page.
Half of a section is 320 acres; a quarter section is 160 acres; a quarter of a quarter is 40 acres.
A quarter of a quarter of a quarter comes to 10 acres, and descriptions do nest that far.
One acre equals 43,560 square feet, which is the bridge between survey acreage and lot dimensions.
Sections run from number one in the northeast corner to number thirty-six in the southeast corner, alternating direction row by row.
Sections that touch a correction line or a body of water may be irregular, so a nominal fraction there is an estimate rather than a certainty.
Reading a Description From Right to Left
The single most useful habit for these items is refusing to read the description in the order it is written.
A rectangular survey description is written from the smallest parcel outward, but it resolves from the largest inward. Start at the far right, which names the section, and work back toward the left, dividing as you go. Each comma or 'of' in the description is one more division.
For acreage, that gives a mechanical routine. Begin at 640 acres for the full section. Divide by two for every half named, by four for every quarter named, and keep going until you reach the leftmost term. The order of the terms does not affect the final acreage, so a candidate who divides correctly cannot land on the wrong number.
Watch for descriptions joined by 'and' rather than nested by 'of'. Two tracts joined with 'and' are separate parcels whose acreages are computed independently and then added. Treating a compound description as a single nested one is the most common error on these items, and the wrong answer is usually one of the four choices.
For location rather than acreage, sketch the section as a box and split it as you read backward. Mark the named half or quarter at each step. Four quick pencil strokes answer questions about which corner a parcel occupies or which described tract adjoins another, and they do it faster than reasoning in your head under time pressure.
Try Two
Both are original items written for practice. Work them on paper before reading the explanation.
Question 1
A parcel is described as the S 1/2 of the NE 1/4 of the SE 1/4 of a section. How many acres does it contain? (A) 20 acres (B) 40 acres (C) 80 acres (D) 160 acres
A. Read the description from the right. The section holds 640 acres. Its SE quarter is 160 acres. The NE quarter of that piece is 40 acres. The south half of the remainder is 20 acres.
Question 2
A rancher owns the NW 1/4 and the E 1/2 of the SW 1/4 of the same section. What is the total acreage, and where does the numbering place that section if it sits directly south of section four? (A) 200 acres, section five (B) 200 acres, section nine (C) 240 acres, section nine (D) 240 acres, section eight
C. The two tracts are joined by 'and', so compute each separately and add: the NW quarter is 160 acres, and the east half of the SW quarter is 80 acres, for 240 acres. On numbering, the top tier runs six, five, four, three, two, one from west to east, and the second tier reverses, running seven through twelve eastward. That places section nine directly below section four.
Questions Candidates Ask About the Grid
Does every state use the rectangular survey system?
No. It was created to dispose of federal public land, so it covers the states carved out of the public domain. The original colonies and several other states were settled and described before the system existed and still rely on metes and bounds descriptions or recorded plats. Some states contain both in different regions.
Why do some sections contain more or less than 640 acres?
Because the earth is curved and the grid is not. Range lines converge going north, so the surveyors built in correction lines and guide meridians to restart the measurement. Sections adjoining those seams absorb the discrepancy. Shorelines and navigable water create the same effect, leaving fractional parcels surveyed individually as government lots.
What is the difference between a township and a township line?
A township is the six mile square of land. Township lines are the east-west lines that create the tiers those squares sit in, while range lines are the north-south lines that create the columns. The word also names a unit of local government in some states, which is unrelated to the survey usage.
Do I need the principal meridian in an answer?
For a complete legal description, yes. Township three north, range two east describes a location in dozens of places nationally, and only the named principal meridian makes it unique. Exam items about the adequacy of a description often turn on precisely that omission.
How do these descriptions interact with platted subdivisions?
They nest. A developer typically starts with a tract described by the rectangular survey, records a subdivision plat over it, and from that point forward lots are conveyed by lot, block and plat reference. The underlying grid description remains in the chain of title and still describes the outer boundary of the platted land.