Introduction
All lands in the public domain are subject to subdivision by a rectangular system of surveys called the Public Land Survey System (PLSS), established and regulated by the Bureau of Land Management. The original public domain includes 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 western States.
Under Congressional mandate, cadastral surveys of public lands were undertaken to create parcels suitable for disposal by the Government. The PLSS was developed for this purpose. The PLSS is a rectangular survey system that typically divides the land into 6-mile square townships, which are further subdivided into 1-mile square sections. The extension of the rectangular system of surveys over the public domain has been in progress since 1785. These surveys form the basis of patents issued when public lands pass out of Federal ownership.
Certain lands were excluded from the public domain and not subject to survey and disposal. These lands include the beds of navigable bodies of water, national installations such as military reservations and national parks, and areas such as land grants that had already passed to private ownership prior to subdivision by the Government.
Data describing the PLSS is required by Federal surface and mineral management agencies, as well as any organization concerned with land ownership in the 30 western States that were formed from the public domain. Additionally, many agencies have encoded natural resource or environmental inventory data based on the PLSS.
The Rectangular System of Surveys
The rectangular system of surveys was devised to subdivide public domain lands. It divides the land into townships 6-mile square by north and south lines that run according to the true meridian and by others crossing the north and south lines at right angles. Townships are, in turn, subdivided into sections of, as nearly as possible, 640 acres by parallel lines that run east to west and south to north at 1-mile intervals. Corner monuments are placed along all lines as they are surveyed at 1/2-mile (quarter-section) intervals. The monumentation is intended to establish a permanent marking of the lines and to fix the corner positions so that the location of the surveyed lands can always be definitely known.
With respect to the ideal rectangular plan, a survey of the public lands is accomplished by establishing, in order, the following:
Independent initial point
This is the point from which the survey of the principal meridian and base line, controlling the survey of the public lands in a given area, is initiated. There are 46 separate surveys in the nationwide system. Of these, only eight in Ohio and Indiana (commenced between 1785 and 1805) have no initial point as defined.
Principal meridian
This is a line extending north and south along the astronomic meridian passing through the initial point. It serves as the origin for the survey of township boundaries along the parallels.
Base line
This is a line extending east and west along a true parallel of latitude passing through the initial point. It serves as the origin for the survey of meridional township boundaries.
Standard parallels (correction lines)
These are auxiliary governing lines that extend east and west from the Principal Meridian, generally at intervals of 24 miles (four townships) north and south of the base line. In many surveys run before 1850, correction lines were run at intervals of 30, 36, or 60 miles. Standard parallels are used to take up error in the rectangular plan caused by the convergence of meridians.
Guide meridians
These are auxiliary governing lines that are projected north from points established on either the base line or standard parallels, generally at intervals of 24 miles east and west of the principal meridian. Guide meridians terminate at the point of intersection with another standard parallel.
Township exteriors
These are lines surveyed at 6-mile intervals that conform to meridians and parallels within established limits. Meridional township boundaries (range lines) are run from south to north and terminate at the point of intersection with a standard parallel. Latitudinal township boundaries (township lines) are run from east to west through corners established on the Meridional lines. Townships are numbered to the north and south commencing with number 1 at the base line, and with range numbers to the east and west commencing with number 1 at the principal meridian. The township number is used in conjunction with the range number to indicate the coordinates of a particular township with respect to the initial point.
Subdivision of townships
The south and east boundaries of a township are normally the governing lines of sub divisional surveys. Meridional section lines are initiated at the section corners at the south boundary of the township and are run north parallel to the east boundary. They are not continued north beyond a section corner until the connecting latitudinal section lines have been surveyed. Latitudinal section lines are run west to east parallel to the south boundaries of the respective sections. Any fractional measurement is placed in the north or west 1/2 mile of the township. A normal township is divided into 36 sections numbered commencing with number 1 in the northeast section of the township, proceeding west to section 6, then south to section 7, then east to section 12, and so on, to number 36 in the southeast section.
Half townships may be created in instances where the distance between the regular positions of township boundaries is so great that the application of normal rules of subdivision would result in sections elongated in excess of 120 chains (7,920 feet). Half ranges may be created in instances where the distance between the regular positions of township boundaries is so great that the application of normal rules of subdivision would result in sections elongated in excess of 120 chains (7,920 feet).
Subdivision of sections
Subdivision of sections into aliquot parts or irregular lots is controlled by the previously established section and quarter-section corners. This subdivision may be accomplished by field methods or protracted on the official plat. Subdivision lines and corners are shown on quadrangle maps, usually to the section level with some quarter section corners shown, to the extent that their positions can be determined from evidence on the ground. During field work, enough corners are located to accurately position the network of public land lines from official plats. Although the PLSS is mapped to meet National Map Accuracy Standards, its depiction is not intended to be official or authoritative; it is presented as useful reference information. The only legal basis for determining land boundaries remains the original survey.
Survey Corners
Survey corners are points on the surface of the Earth that represent extremities of a subdivision of the public lands, generally at the intersection of two or more surveyed lines. The classification of a corner describes the relative corner location, type of survey, or the controlling aspects of the corner. A survey corner is identified by unique symbology or labeling on the map only when the monumented point has been recovered in the field.
The following is a list of the types of survey corners found on USGS quadrangle maps:
Angle point
This is a point on a survey where the alignment or boundary deflects from a straight line.
Amended monument
A survey monument whose position no longer marks the true position for the corner, but which is connected by course and distance to the new corner. There are two primary applications of amended monuments:
(1) If another survey such as a mineral survey, homestead entry, small holding claim, or right of way or reservoir survey has been tied to a monument that has been found to be out of position, the monument is marked "AM" and connected by course and distance to a new, correctly positioned monument, and (2) If a recovered closing corner is not at the true point of intersection of the line it is closing to, a new monument will be placed at the true point of intersection and the old monument will be marked "AM" and connected by course and distance.
Land grant or other special survey corner
A monumented point on a land grant, tract, donation land claim, U.S. Survey, Homestead Entry Survey, or Indian Allotment.
Meander corner
The beds of navigable bodies of water are not public domain and are not subject to survey and disposal by the United States. At every point where a section line intersects the banks of such a feature, a meander corner is established, and a metes and bounds traverse, called a meander line, is run to segregate the water area from the public lands. Meander lines are not mapped.
Quarter-section corner
Quarter-section corners are found at the extremity of a quarter-section boundary, theoretically located halfway (40 chains) between section corners. Normally, quarter-section corners are not searched for or plotted unless there is a bend in the line at the corner or the section corners on either side cannot be recovered.
Section Corner
A section corner is established at the extremity of a PLSS section boundary, where two or more section lines meet or cross. It is surrounded by one or more distinct sections.
U.S. Mineral Monument and U.S. Location Monument
This is a monumented reference for one or more mineral surveys or for an isolated special survey. The monument is established during surveys of the irregular boundaries of mining claims when no public land corners have been established in the vicinity. When the public land surveys are subsequently extended to the area, the mineral monument is tied to a regular section corner. This type of monument may also be used in any situation where no corner of an existing survey is available to provide a satisfactory connection for an isolated special survey. In most cases the monument does not fall on a public land line.
Witness corner
A witness corner is established if the true corner cannot be marked in the usual manner because of obstructions or difficult terrain. It is located on the section line within 10 chains (660 feet) or anywhere within 5 chains (330 feet) of the actual corner. Normally, only one witness corner is established in each instance. For example, a witness corner is commonly established on secure ground when the true position of a meander corner falls at a point where the monument would likely be destroyed by the effects of tide, waves, or ice.
Witness point
This is a monumented point on a survey line marking an important location remote from and not related to a regular corner (for example, a road or stream crossing).
Survey Lines
Survey lines in the PLSS category represent the build up of the land net from the section corners whose monuments have been recovered in the field. The accuracy of the section lines depends on the relative accuracy and density of the recovered section corners.
Solid lines connect reliable section corners and represent survey lines plotted to meet National Map Accuracy Standards (40 feet at the 1:24,000 scale). Dashed section lines connect questionable section corners and represent survey lines that do not meet National Map Accuracy Standards, but are plotted within 200 ft at 1:24,000-scale.
The Bureau of Land Management has defined protracted land lines for all areas of Alaska not yet subdivided by ground surveys and some other areas in the continental United States. The unsurveyed land lines represent theoretically perfect subdivisions. Protracted land lines have been shown as solid gray lines on Alaska quadrangle maps. The current symbol for protracted land lines is a solid red line. The protracted land lines for all suspended and unsurveyed townships in the conterminous United States are not shown at the 1:24,000 scale unless they are provided by the Forest Service for portrayal on quadrangle maps produced through the single edition initiative. Protracted land lines are shown by dashed red lines on 1:100,000-scale maps. Land lines may be omitted from maps in public land States when they have not been established by survey or where there is insufficient field evidence to position the land net to established standards. A note in the map margin explains the reason for the omission.
Survey Areas
The States within the public domain contain a variety of surveys, such as land grants, lands subdivided by rectangular surveys, and lands subdivided by special surveys. Specific types of survey areas within the public domain that are shown on USGS quadrangle maps are:
PLSS Area
An area of land that was part of the original public domain and which was subject to subdivision by the Public Land Survey System. The PLSS is a rectangular survey system that typically divides the land into 6- mile square townships, which are further subdivided into 1-mile square sections.
Homestead Entry Survey
A Homestead Entry is an entry under the U.S. laws for the purpose of acquiring title to a portion of the public domain under the Homestead laws. A Homestead Entry is a metes and bounds survey entered under the Act of June 11, 1906 as amended. Homestead Entries are not mapped unless they define the limits of the land net.
Donation Land Claim
Tracts of land, 320 or 640 acres in size, were allocated to settlers in the Oregon Territory (Oregon and Washington) who had resided on and cultivated the land for 4 years under the Donation Act of September 27, 1850; to settlers in Florida under the Act of August 4, 1842; and to settlers in the New Mexico Territory (New Mexico and Arizona) under the Act of July 22, 1854. These tracts were part of the original public domain and were surveyed prior to the rectangular surveys. Donation Land Claims are not mapped unless they define the limits of the land net.
Land Grant
A land grant is an area of land to which title was conferred by a predecessor government and confirmed by the U.S Government after the territory in which it is situated was acquired by the United States. These lands were never part of the original public domain and were not subject to subdivision by the rectangular surveys.
Private Extension of the Public Land Survey
The term "private" refers to any public land survey not performed by or contracted by the Bureau of Land Management. They include, for example, Bureau of Indian Affairs surveys on Indian lands. These areas are also assigned origin of survey, township, range, and section number parameters as appropriate.
Tract
The term tract is used to mean a parcel of land that lies in more than one section or cannot be identified in whole as part of a particular section. Tract boundaries are not mapped unless they define the limits of the land net.
United States Survey
A metes and bounds survey executed to comply with one of various regulations for entry of public lands in Alaska. U.S. Surveys are not mapped unless they define the limits of the land net.
Indian Allotment
An allocation of a parcel of public lands or Indian Reservation lands to a Native American for his or her individual use in the lower 48 States. Indian Allotments are not mapped unless they define the limits of the land net.
Irregular Rectangular Surveys in Ohio and Indiana
The rectangular system of surveys was in its initial stage of development when the State of Ohio was surveyed, beginning in 1785. Because the current system of principal meridians and baselines was not yet established, the Ohio surveys used a number of different reference meridians and base lines. Eight public land surveys were conducted having no initial point as an origin for both township and range numbers. These include seven surveys in Ohio and one in Indiana. They commenced between 1785 and 1805, a period when the laws prescribing the subdivision of the public domain were in flux. Although rectangular in nature, these surveys do not strictly conform to the current plan. Within several surveys, townships depend on crooked rivers for base lines. This causes offsets in the township tiers and irregular sequences of numbering. In addition, the subdivision of townships is not consistent. The current system of numbering sections within a township was not adopted until passage of the Land Act of May 18, 1796. Prior to this time, the original Ordinance of May 24, 1785, applied, in which sections were numbered commencing with number 1 in the southeast corner of the township, proceeding north to section 6, then continuing with section number 7 in the southernmost section of the next column to the west, and proceeding north to section 12, and so on, to number 36 in the northwest section.
Source http://www.topodepot.com/USGS_PLSS_BACKGROUND.aspx