The PLSS: Township, Range & Section
Most public land in the western United States is described not by a street address or a pair of coordinates but by a rectangular grid laid down by federal surveyors. The Public Land Survey System (PLSS) is that grid. It is the way the Bureau of Land Management (BLM) subdivides and describes land across roughly thirty southern and western states, and it is the language in which nearly every federal mining claim is written. If you can read a township, range, and section, you can find a parcel on a map and understand exactly which ground a claim covers.
Principal Meridians and Baselines
The PLSS is built outward from fixed starting points. At each initial point a surveyor runs a north-south line called a principal meridian and an east-west line called a baseline that runs parallel to the Equator. Every township and range in that survey area is counted from this cross, and the survey area takes the name of its principal meridian — for example, the Mount Diablo Meridian or the Boise Meridian. Because the system was extended piecemeal as the country grew, there are dozens of independent principal meridians, which is why a complete land description must always name the meridian it belongs to. Without it, "Township 10 South, Range 21 East" is ambiguous, because that same designation exists under more than one meridian.
Townships, Ranges, and Sections
From the initial point, surveyors establish lines at six-mile intervals in every direction. Each six-by-six-mile square is a township. Its position is given two ways: by township number counting north or south of the baseline, and by range number counting east or west of the principal meridian. So "Township 14 South, Range 34 East" means the fourteenth tier south of the baseline and the thirty-fourth column east of the meridian.
Each township is divided into 36 sections, and each section is nominally one square mile — 640 acres. Sections are numbered in a back-and-forth, boustrophedon pattern: number 1 sits in the northeast corner, the count runs west to number 6, drops down a row and runs east, and so on, weaving down the township to number 36 in the southeast corner. This is the single most useful pattern to memorize, because it lets you find any section by eye once you know where Section 1 is.
Subdividing the Section: Quarters and Aliquot Parts
A section is rarely claimed or described whole. It is split into aliquot parts — legal subdivisions made by repeatedly halving or quartering. A section divides into four quarter sections (NE, NW, SE, SW) of about 160 acres each. A quarter section divides again into four quarter-quarter sections of about 40 acres; the BLM treats the 40-acre quarter-quarter as the standard land unit for management. The halving continues as needed: a quarter of a quarter-quarter is about 10 acres, and a further quarter about 2.5 acres. Where lakes, rivers, or curved survey boundaries make a regular grid impossible, the leftover pieces are surveyed as numbered government lots instead of clean aliquot parts.
This nesting is how a precise description is read from largest to smallest. The description "E1/2 NE1/4 NE1/4, Section 2, Township 10 South, Range 21 East, Mount Diablo Meridian" is read right to left: start with the section, take its northeast quarter, then the northeast quarter of that, then the east half of that — narrowing from 640 acres down to about 20 acres on a specific patch of ground.
Why It Matters for Mining Claims
For a placer mining claim, the BLM expects the location to be described by legal subdivision — meridian, township, range, section, and aliquot part down to at least the quarter-quarter — rather than by guesswork on the ground. Lode claims, which follow a vein, are instead described by a metes-and-bounds survey tied back into the PLSS. Either way, the township-range-section framework is what lets you confirm the land is open, see whether prior claims already cover it, and file a description the BLM and the county will accept. USGS topographic maps print the PLSS grid and its descriptions, and BLM master title plats and claim records are organized by it. Always verify land status and existing claims with the BLM or official sources before relying on any description.
In Lodester
Lodester's BLM land and claims panel is built on the same framework. When you tap a recorded claim, its legal description appears in PLSS terms, and the skills above let you read it: identify the meridian, then the township and range to find the right six-mile square, then the section number to pinpoint the square mile, then work through the aliquot parts from the section inward to the exact parcel. A dedicated PLSS layer is planned, which will draw the township, range, and section grid directly over the map so a written description and the ground beneath it line up at a glance.
This page is general reference information, not legal advice. Always confirm land status, claim boundaries, and filing requirements with the BLM or official sources before acting.