The Public Land Survey System (PLSS), often called township and range, is the rectangular survey grid used to describe the public lands of the United States: from an initial point, surveyors run a principal meridian and a base line, divide the land into townships of six nominal miles on a side, and divide each township into 36 sections of about one square mile (640 acres), which are split further into aliquot parts such as quarter sections.
A PLSS legal description reads like an address on a grid. "The NE/4 of the SW/4 of Section 12, Township 5 North, Range 3 West" means: find the principal meridian and base line that govern the state; count five townships north of the base line and three ranges west of the meridian to find a six-mile square; within it find Section 12; within that section take the southwest quarter, and within that quarter the northeast quarter. The result is a nominal 40-acre tract. Every piece of the description narrows the one before it.
The Bureau of Land Management (BLM), which runs the federal cadastral survey, describes the rectangular system as a grid of lines based on a true meridian and started from an initial point. From that point the surveyor runs a north-south principal meridian and an east-west base line.
Lines are then laid out at six-nominal-mile intervals. Counting north or south from the base line gives the township number (Township 5 North is the fifth six-mile tier north of the base line). Counting east or west from the principal meridian gives the range number (Range 3 West is the third six-mile column west of the meridian). Each six-by-six-mile square is itself called a township.
Because meridians converge toward the north, a perfect grid is impossible on a curved earth. To correct for that convergence, surveyors establish guide meridians and standard parallels every 24 miles from the initial point, according to the BLM.
Each township is divided into 36 sections of one square nominal mile. Numbering starts with Section 1 in the northeast corner and runs back and forth across the rows, right to left and then left to right, ending with Section 36 in the southeast corner. The BLM notes the pattern means a section always adjoins the sections numbered just before and after it.
Portions of a regular section are described as aliquot parts, exact fractions of the whole. A quarter is named by its corner (NE/4, NW/4, SW/4, SE/4); a half by its side (N/2, S/2, E/2, W/2). The BLM treats the 40-acre quarter-quarter as its standard land unit for management, and quarter-quarters can be divided again into 10-acre and 2.5-acre parts.
Not every section holds 640 acres. The sections along the north and west sides of a regular township are often irregular and are divided into numbered lots instead of aliquot parts. Lots also appear where special surveys or rivers and lakes leave areas that cannot be described in aliquot parts. A lot may hold more or less than 40 acres, so its acreage comes from the official plat, not from arithmetic.
| Unit | Example | Nominal acres |
|---|---|---|
| Township | T5N R3W | 23,040 (36 sections) |
| Section | Section 12 | 640 |
| Half section | N/2 of Section 12 | 320 |
| Quarter section | SW/4 of Section 12 | 160 |
| Half of a quarter | E/2 of the SW/4 | 80 |
| Quarter-quarter | NE/4 of the SW/4 | 40 |
| Quarter of a quarter-quarter | NW/4 of the NE/4 of the SW/4 | 10 |
| Next division | NE/4 of the NW/4 of the NE/4 of the SW/4 | 2.5 |
| Lot | Lot 3 of Section 6 | As shown on the plat |
Read a PLSS description from right to left, from the largest unit to the smallest. First identify the meridian, because "Township 5 North, Range 3 West" exists once for every meridian. Then locate the township and range, then the section, then each aliquot call in turn. Watch the punctuation: the BLM study guide stresses that where commas and semicolons fall changes what a description includes.
In a regular 640-acre section, multiply 640 by each fraction in the call to get the tract's nominal acreage. The NE/4 SW/4 is 640 × 1/4 × 1/4 = 40 acres; the E/2 SW/4 is 640 × 1/2 × 1/4 = 80 acres. That arithmetic does not hold in an irregular section or for a lot: use the acreage on the official plat (BLM's GLO Records hold the survey plats). What a mineral owner owns in that tract is a further fraction, which is how net mineral acres are calculated.
Section lines also frame many drilling and spacing units, so the same description that locates your land often tells you which unit a well is in.
Most owners start from a deed, a lease, a division order or a tax statement, all of which normally carry the legal description. If you have only an address or a map location, these official tools help:
The rectangular system dates to the Land Ordinance of 1785. The BLM's history of the rectangular survey system traces the first surveys under the ordinance to the Seven Ranges, begun on the north bank of the Ohio River in September 1785, and describes the ordinance as consolidating the better features of colonial practice rather than inventing a new one. The Oklahoma Historical Society summarizes it the same way: established in 1785 and first applied to the Northwest Territory, the system divided the public domain into standard units called sections.
As the public domain grew, new principal meridians were established, each with its own initial point and base line. A description is meaningless without its meridian, which is why deeds and plats name it.
The table below lists the meridians that govern surveys in the main producing states, as described in the General Land Office's 1894 Manual of Surveying Instructions, reproduced in the BLM's history of the rectangular survey system. Texas, Pennsylvania and Kentucky land did not pass from the federal public domain and is described differently; see the guides linked below.
| State | Governing meridian(s) | Notes |
|---|---|---|
| Oklahoma | Indian Meridian; Cimarron Meridian | Indian Meridian for the former Indian Territory and Oklahoma Territory east of 100° W; Cimarron Meridian west of 100° W (the Panhandle) |
| Louisiana | Louisiana Meridian; St. Helena Meridian | Louisiana Meridian west of the Mississippi River; St. Helena Meridian for the Greensburg and southeastern districts east of the river |
| New Mexico | New Mexico Principal Meridian | The 1894 manual referred the northwest corner to the Navajo Meridian; BLM records that those New Mexico surveys were cancelled in 1936 |
| Colorado | Sixth Principal Meridian; New Mexico Principal Meridian; Ute Meridian | New Mexico meridian in the Rio Grande valley |
| Wyoming | Sixth Principal Meridian; Wind River Meridian | — |
| Kansas | Sixth Principal Meridian | — |
| Nebraska | Sixth Principal Meridian | — |
| North Dakota | Fifth Principal Meridian | — |
| South Dakota | Fifth Principal Meridian; Sixth Principal Meridian; Black Hills Meridian | Black Hills Meridian north and west of the White River and west of the Missouri River |
| Montana | Principal Meridian, Montana | The BLM history notes it has no other name or number |
| Utah | Salt Lake Meridian; Uintah Meridian | — |
| Arkansas | Fifth Principal Meridian | — |
| Mississippi | Choctaw, Chickasaw, Washington and St. Stephens Meridians | St. Stephens Meridian for the Pearl River district east of the river |
| Alabama | Huntsville Meridian; St. Stephens Meridian; Tallahassee Meridian | Huntsville in the northern district, St. Stephens in the southern district; the Tallahassee Meridian controls a narrow strip in Alabama |
| Michigan | Michigan Meridian | — |
| California | Mount Diablo, San Bernardino and Humboldt Meridians | — |
| Texas | None: not a PLSS state | Original land surveys and abstract numbers recorded with the General Land Office |
| Pennsylvania | None: not a PLSS state | Land passed from the colony and Commonwealth by warrant, survey and patent |
| Kentucky | None: not a PLSS state | Land passed by patent from Virginia or Kentucky; most patents carry metes-and-bounds descriptions, but the Jackson Purchase in western Kentucky was mapped into ranges, townships and sections under an 1820 state law |
Texas never ran a uniform statewide survey. The Railroad Commission of Texas explains that its original "patent surveys," recorded with the General Land Office, constitute the state's official land survey system, each with an abstract number unique within its county. See Texas land surveys and abstract numbers.
In Kentucky, land passed by patent from Virginia or Kentucky, and most patents describe each tract by metes and bounds; the exception is the Jackson Purchase in western Kentucky, which the General Assembly ordered mapped into ranges, townships and sections in 1820. In Pennsylvania, land passed from the colony and Commonwealth by warrant, survey and patent. Louisiana uses township and range, but its surveyors laid out river lots and confirmed colonial land claims before the regular sections; see Louisiana land surveys. For the Indian and Cimarron meridians, see Oklahoma township and range. State guides also cover New Mexico, North Dakota, Colorado, Wyoming and West Virginia.
This page is general information, not legal advice. A title examiner or licensed surveyor should confirm what a specific description covers.
Texas Land Surveys and Abstract Numbers
How to Prove You Own Mineral Rights
Oil & Gas Encyclopedia — all terms
Educational information only — not legal, tax, or investment advice. Consult a qualified attorney, CPA, or landman about your specific situation.
Township and range is the common name for the Public Land Survey System, the rectangular grid used to describe the public lands of the United States. Townships are counted north or south of a base line and ranges east or west of a principal meridian, in six-mile steps.
Look at your deed, lease, division order or tax statement, which normally state the legal description. Without one, the BLM General Land Office Records site has a map search that accepts township and range, and county deed records and tax rolls list each tract's description.
A regular section is one square nominal mile, or 640 acres. A quarter section is 160 acres and a quarter-quarter is 40 acres. Sections along the north and west sides of a township are often irregular and divided into lots, which can hold more or less.
A regular township is six nominal miles on a side and contains 36 sections, or 23,040 acres. Actual area varies where convergence or earlier surveys made the township irregular.
Section 1 is in the northeast corner. Numbering runs right to left across the top row, then left to right across the next, back and forth, ending with Section 36 in the southeast corner.
Township 5 North, Range 3 West: the six-mile square that is the fifth tier north of the base line and the third column west of the principal meridian. It must be read with the meridian named in the description.
The north-south line, run from an initial point, from which ranges are counted east and west. Each state's surveys refer to one or more named meridians, such as the Indian Meridian in Oklahoma or the Sixth Principal Meridian in Kansas.
No. Texas was never surveyed under the PLSS. Its land is described by original surveys, blocks, sections and abstract numbers recorded with the Texas General Land Office.
An exact fraction of a regular section, such as the NE/4 (a quarter) or the N/2 (a half), or a fraction of those fractions, such as the NE/4 of the SW/4 (a 40-acre quarter-quarter).
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