Quarter Section
One of the four parts of a PLSS section, nominally 160 acres, named NE1/4, NW1/4, SW1/4, or SE1/4 and bounded by straight lines between opposite quarter corners.
Detailed Definition
A quarter section is one of the four parts of a section in the Public Land Survey System (PLSS). It is nominally 160 acres and is named by its position: NE1/4, NW1/4, SW1/4, or SE1/4.
BLM's Glossary of Surveying and Mapping Terms defines a quarter section as "one-fourth of a section, containing 160 acres more or less," and as one of the aliquot parts of a section, normally about half a mile on each side.
How the lines are drawn
The quarter-section lines are the section's center lines. BLM's Specifications for Descriptions of Land (2017) says the section is subdivided "by running straight lines from the established quarter-section corners to the opposite corresponding quarter-section corners." BLM's Manual of Surveying Instructions (2009) calls the crossing point "the legal center of the section," and notes that "straight lines" here means lines of constant bearing (section 3-114).
The rule comes from federal law. Boundary lines "which have not been actually run and marked shall be ascertained, by running straight lines from the established corners to the opposite corresponding corners" (43 U.S.C. 752). The Act of February 11, 1805, directed that the public lands be subdivided into quarter sections "by protraction not by survey" (Manual section 1-20). BLM surveyors do not subdivide sections in the field unless the special instructions call for it. The protracted quarter-section lines are shown on the official plat as dashed straight lines (sections 3-99 and 3-103).
Why 160 acres is nominal
In a regular section, each quarter section is returned as 160 acres. In the sections along the north and west boundaries of a township, the township's excess or deficiency goes into lots, so those sections contain half-quarter sections and lots instead of full quarters (section 3-103). The Specifications warn not to write "lots 1 and 2, and S1/2NE1/4" as the NE1/4 of such a section, because that description "is ambiguous and subject to more than one interpretation."
Dividing it further
A quarter section splits into four quarter-quarter sections of nominally 40 acres, written, for example, SW1/4NE1/4. The quarter-quarter corners are fixed "as nearly as possible equidistant or proportionate measurement from two corners which stand on the same line" (section 3-117). Under the mining laws the smallest legal subdivision is 10 acres, a quarter of a quarter-quarter (section 3-2).
Order and form
In a description, the Specifications list quarter sections in the order NE, NW, SW, SE, and describe all parts of one quarter before moving to the next.
Why it matters in research
Quarter sections are a common unit in mining claim filings, federal leases, and land status records. Because the center of the section is set by the quarter corners, a lost or doubled quarter corner moves every quarter line in the section. In the north and west sections of a township, a description that treats lots as a full quarter section may not match the official plat.
Related Terms
PLSS
The Public Land Survey System, the rectangular survey system that divides the public lands into townships, ranges, and sections and serves as the basis for describing them.
Legal Description
The written statement in a deed, patent, lease, or order that identifies the land it covers, precisely enough that a surveyor can locate it on the ground.
Aliquot Part
A legal subdivision of a PLSS section made by dividing it into halves or quarters, such as the NE1/4 or the SW1/4NE1/4. Lots are the other kind of legal subdivision.
Range
In the PLSS, a north-south column of townships, numbered east or west from the principal meridian. R. 20 E. is the twentieth column east of the meridian.
Township
In the PLSS, the unit of survey: a nominal six-mile square of 36 sections, and also the row of such squares numbered north or south of the base line.
Section
The unit of subdivision of a PLSS township, nominally one mile square and 640 acres. Each township has 36 sections, numbered from 1 in the northeast to 36 in the southeast.
Lot
In the PLSS, a numbered legal subdivision of a section that is not an aliquot part, created where a section cannot be divided evenly, such as along township edges or water.