What is PLSS?

The Public Land Survey System (PLSS) is a way of subdividing and describing land in the United States. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior, Bureau of Land Management (BLM).

The PLSS is used to divide public domain lands, which are lands owned by the Federal government for the benefit of the citizens of the United States. The original public domain included the land ceded to the Federal Government by the thirteen original States, supplemented with acquisitions from native Indians and foreign powers. It encompasses major portions of the land area of 30 southern and western States. Since the original PLSS surveys were completed, much of the land that was originally part of the public domain has been transferred to private ownership and in some areas the PLSS has been extended, following similar rules of division, into non-public domain areas. PLSS rules of division are explained below. For areas that were once part of the public domain, legal land descriptions are usually written in terms of PLSS descriptions.

The PLSS typically divides land into 6-mile-square townships, which is the level of information included in the National Atlas. Townships are subdivided into 36 one-mile- square sections. Sections can be further subdivided into quarter sections, quarter-quarter sections, or irregular government lots. Normally, a permanent monument, or marker, is placed at each section corner. Monuments are also placed at quarter-section corners and at other important points, such as the corners of government lots. Today permanent monuments are usually inscribed tablets set on iron rods or in concrete. The original PLSS surveys were often marked by wooden stakes or posts, marked trees, pits, or piles of rock, or other less-permanent markers.

The PLSS actually consists of a series of separate surveys. Most PLSS surveys begin at an initial point, and townships are surveyed north, south, east, and west from that point. The north-south line that runs through the initial point is a true meridian and is called the Principal Meridian. There are 37 Principal Meridians, each is named, and these names are used to distinguish the various surveys. The east-west line that runs through the initial point is called a base line. This line is perpendicular to the Principal Meridian.

Each township is identified with a township and range designation. Township designations indicate the location north or south of the baseline, and range designations indicate the location east or west of the Principal Meridian. For example, a township might be identified as Township 7 North, Range 2 West, which would mean that it was in the 7th tier of townships north of a baseline, and in the 2nd column of townships west of a baseline.  A legal land description of a section includes the State, Principal Meridian name, Township and Range designations with directions, and the section number: Nebraska, Sixth Principal Meridian T7N, R2W, S5.

While the original PLSS surveys were supposed to conform to official procedures, some errors were made due either to honest mistakes or to fraudulent surveys. Existing surveys are considered authoritative, and any new surveys must work from existing corners and surveys, in spite of errors in the original surveys and variations from the ideal. This sometimes results in sections that are far from square, or that contain well over or under 640 acres.

The early surveys in Ohio and Indiana were done when the system currently in use had not yet been fully developed. While these surveys have townships that are 6 miles square, the numbering system used and the types of starting points for the surveys are different from those used elsewhere in the United States. These surveys are also named, although the names are not based on Principal Meridians. Further information on these irregular surveys can be found in the references listed at the end of this article. In particular, see the Background Information on the Public Land Survey System.

In Louisiana, parcels of land known as arpent sections or French arpent land grants also pre-date the PLSS, but are treated as PLSS sections. An arpent is a French measurement of approximately 192 feet, and a square arpent (also referred to as an arpent) is about 0.84 acres. French arpent land divisions are long narrow parcels of land usually found along the navigable streams of southern Louisiana, and also found along major waterways in other areas. This system of land subdivision was begun by French settlers in the 1700s, according to typical French practice at the time and was continued by both the Spanish and by the American government after the acquisition of the Louisiana Purchase. A typical French arpent land division is 2 to 4 arpents wide along the river by 40 to 60 arpents deep, while the Spanish arpent land divisions tend to be 6 to 8 arpents wide by 40 arpents deep. This method of land division provided each land-owner with river frontage as well as land suitable for cultivation and habitation. These areas are given numbers just like standard sections, although the section numbers frequently exceed the normal upper limit of 36.