What Is the Public Land Survey System (PLSS)?
The Public Land Survey System (PLSS) is the rectangular grid that the United States federal government used to subdivide the public domain after the Land Ordinance of 1785. It covers 30 states — from Ohio westward, plus Alabama, Mississippi, Florida, and Louisiana — and provides the spatial reference framework for hundreds of millions of acres of private, state, and federal land.
Principal Meridians and Base Lines
Each PLSS state (or group of states) is organized around a named principal meridian and a perpendicular base line. Idaho and Nevada, for example, are referenced to the Boise Meridian. Ohio has three separate meridians. The intersection of the principal meridian and base line is the origin point for the entire grid in that region. There are 37 principal meridians in the contiguous United States and Alaska.
Townships and Ranges
Moving north or south from the base line creates township tiers, numbered T1N, T2N, T3N (north of the base line) or T1S, T2S (south). Moving east or west from the meridian creates ranges, numbered R1E, R2E or R1W, R2W. A six-mile-square block identified by both numbers — for example, Township 3 North, Range 1 East, Boise Meridian — is simply called a township, and it contains 36 sections.
Sections
Each township is divided into 36 one-mile-square sections, each nominally containing 640 acres. Sections are numbered 1–36 starting in the northeast corner and snaking back and forth to end at Section 36 in the southeast corner. Section 1 is always the northeast section; Section 6 is the northwest.
Sections are further subdivided into quarter sections (NE¼, NW¼, SE¼, SW¼ — each nominally 160 acres), quarter-quarter sections (40 acres each), and government lots along the north and west edges of townships where the grid does not divide evenly.
PLSS Identifiers in Legal Descriptions
A typical PLSS reference in a metes and bounds description looks like: "…in the SE¼ of Section 14, Township 3 North, Range 1 East, Boise Meridian, Ada County, Idaho." This is the aliquot part — the fractional subdivision of the section that identifies where the parcel sits on the grid. The metes and bounds traverse then describes the exact boundary within that aliquot.
Corner Monuments and the GCDB
Original PLSS surveys set physical corner monuments — brass caps, iron pipes, stone mounds — at section corners, quarter corners, and some sixteenth-section corners. The Bureau of Land Management's Geographic Coordinate Data Base (GCDB) holds State Plane coordinates for these monuments, derived from GPS reoccupation and tie-in surveys conducted over several decades. When Legal-Plot geo-locates a description, it queries the GCDB to retrieve the coordinates for the corners referenced in the description, then rotates and places the metes and bounds traverse so it aligns with those authoritative control points.
Why This Matters for Legal Descriptions
The PLSS corner serves as the anchor that ties an abstract metes and bounds traverse to a real geographic location. Without it, you know the shape and size of a parcel but not where it sits on the earth. With it, you can generate State Plane coordinates, compute latitude and longitude, overlay the parcel on aerial imagery, and export it to any GIS platform — all from the text of a deed.