PLSS CadNSDI – PLSS First Division (Sections)

This is the fifth of a series of documents that describe the contents of the PLSS CadNSDI data set.

The PLSS First Division is most commonly the Section.  Almost all PLSS CadNSDI users will have sections for the first division and this is also the most commonly known name for these components of the PLSS CadNSDI.  For simplicity many implementations will name the first division Section, and that is perfectly compliant with the standard.  The feature classes can have whatever alias works well in any jurisdiction. 

But it is important to realize that not all townships are divided into sections and it is sometimes important to be able to recognize the variations and to identify these divisions correctly in land descriptions or in data use.

First divisions do NOT overlap and all of the first divisions in a Township should completely cover or completely account for all of the area in a PLSS Township, except meandered water areas.

Typically sections are numbered in Boustrophedon order from 1 to 36, nominally defining one mile square areas. Boustrophedon meaning the numbers move across the township back and forth from east to west and then west to east much as oxen would plow the ground.  However, as with most things cadastral, there are many exceptions.  Some of these being

·      Sections are not always numbered starting in the Northeast corner of the Township.

·      There can be more than 36 sections in a Township.

·      Section numbers may be duplicated in a Township.

·      Sections are rarely one mile by one mile in size.

A typical PLSS Township with normal section divisions is shown below

Typical PLSS Township and Section Division

The attributes in the standard for the PLSS First Division are listed in the table below.  And as with the other feature classes in the standard the field lengths and aliases are locally configurable.  Additional fields or attributes can be appended to the feature classes.

FieldName	Type	Length	Description	AliasName
PLSSID	String	50	This is the unique identifier for the PLSS Township in which the first division is located. Concatenation of the principal meridian, township, range, and duplication code that form a unique identifier for the township.	Township Identifier
FRSTDIVID	String	50	This is a unique identifier for the first division that is built by appending the first division elements on the Township identifier.	First Division Identifier
FRSTDIVTYP	String	2	This is the type of first division and is commonly the section but may be a lot, parcel, tract or other division.	First Division Type Code
FRSTDIVTXT	String	50	This is the first division type as a text field	First Division Type Text
FRSTDIVNO	String	10	This is the number, letter or designator for the first division of the PLSS Township	First Division Number
FRSTDIVDUP	String	1	This is a code to indicate whether the first division is a duplicated area or identifier	First Division Duplicate
FRSTDIVLAB	String	20	This is the label for the first division that is used for cartographic of web display purposes	First Division Label
SURVTYP	String	2	Code for the type of special survey typically from the codes for the BLM data collection.  Used in this feature to indicate if the feature is unsurveyed or protracted.	Survey Type Code
SURVTYPTXT	String	50	The description of the survey type code.	Survey Type Text
SOURCEDATE	Date	8	The date of the source document	Source Doc Date
SOURCEREF	String	100	The reference to the source document could be a reference to a map or plat or a deed. This could include document type.	Source Doc Link or Reference

The domains for the First Division Type are shown below.  In an implementation the type description is typically more important than the code.  Both the code and description are provided because we have found the codes alone can be a bit confusing for most users.  The codes are used in the Identifiers but it is compliant with the standard to list the type description only. 

First Division Type Code	First Division Type Description	Notes
UA	Unsectionalized Area	Unsectionalized areas are lands that were never divided and no protraction or definition of division was generated.  Over time these areas are expected to have division types added
SN	Section	The section is the most commonly occurring first division and is nominally one mile on a side.  The section numbers are commonly 1 to 36 but section numbers as high as 48 have been identified.
LT	Lot	These are lots that occur only rarely in non-sectionalized Townships.  In these cases the township is divided into lots, but again this is a rare occurrence.
PB	Protracted Block	Protracted Blocks are divisions that provide a defined division in unsurveyed PLSS Townships.  Protracted Blocks are defined by the coordinate values of the corners. These map also have been or be called protraction blocks.
FS **	Fractional Section	Fractional sections are sections that are invaded by water or a protraction such that at least one quarter corner cannot be established and the method for subdividing the section is modified.  The fractional sections may not have been identified in some of the early standard implementations.
QT	Quarter Township	The quarter townships exist in Ohio only.  These are divisions that quarter the township and in some cases the quarter township is quartered again into four lots or parcels.
TR	Tract	There are two uses of Tracts as a first division. (1) PLSS Tracts in the eastern states that should be in the PLSS Special Survey Feature Class but are included in the First Division as a transition to the fully compliant standard. (2) Paragraph 3-122 of the 1973 manual and 3-199 in the 2009 manual  "when administration or disposal requires no subdivision, an island is given a tract number within a township.  In such cases, the section lines need not be extended to the island."
UP *	Unsurveyed Protracted	Unsurveyed Protracted divisions are always a section but have not been measured by survey. The protraction diagram is a plan of survey.
UN *	Unsurveyed Unprotracted	Unsurveyed Unprotracted divisions are always sections but there is no survey or plan of survey.  These divisions have been termed extended PLSS or PLSS grids in some implementations.
UK	Unknown	If the type of first division is not known than this code and description is available as a placeholder until the type of first division can be established.
* The Unsurveyed Protracted and Unsurveyed Unprotracted values reference the survey status or survey condition of a Section.  The first division type for features coded as UP or UN is Section (SN). The Survey type code and description in the PLSS CadNSDI feature classes should be used to indicate the survey status of the feature.  These domains are included as transitional values and will be eliminated over time. ** The fractional section is a legitimate first division type, but thus far all fractional section sections have been identified as sections.

Some of the more frequently occurring First Division types that are not sections are shown Lots, Protracted (or Protraction) Blocks, and Quarter Townships.  Examples of each are shown below.

Protracted Bocks in Utah (Protraction Blocks)

First Division Lots in Wisconsin

Quarter Townships in Ohio

There are many other anomalies and exceptions throughout the PLSS.  Things like duplicated section numbers, sections with numbers greater than 36 and many other unusual configurations.  If there is an unusually situation or configuration, ask the identified data steward for clarification.

PLSS CadNSDI – PLSS Townships

This is the fourth of a series of documents that describe the contents of the PLSS CadNSDI data set.

The PLSS Townships are the primary unit of survey for the PLSS, nominally six miles on a side, usually containing 36 sections. PLSS Townships are numbered from base lines and principal meridians. This feature class provides the polygons for the PLSS Townships. The diagram below illustrates the basic PLSS Township referencing and numbering.

(from http://geology.isu.edu/geostac/Field_Exercise/topomaps/plss.htm last accessed March 2015)

A fairly typical set of Townships with their sections is shown below.  The Townships are designated with the Township (Tier) number and direction and the range number and direction.  For example the Township in the middle is Township 30 North Range 31 East.

But to be complete the Townships also need a principal meridian reference.  The list of Principal Meridians (PM) and their national two digit codes are listed at the end of this article.  A map illustrating the principal meridians can be found at this link

http://www.blm.gov/style/medialib/blm/wo/MINERALS__REALTY__AND_RESOURCE_PROTECTION_/lands_and_realty.Par.1381.File.dat/meridianmap09.jpg

A detailed text describing the history and development of each principal meridian and baseline (Initial Points) can be found at this page (Click on Al White for a link to the book).

http://www.pmproject.org/index.htm

The attributes for the PLSS Township are listed in the following table.  The field lengths for the attributes may be adjusted in some implementations; this is compliant with the standard intent.  The field names and intended content are the focus of the implementation standard.

PLSS Township Attributes

FieldName	Type	Length	Description	AliasName
STATEABBR	String	2	State abbreviation code two letter postal code	State Abbreviation
PRINMERCD	String	2	Principal meridian code from the BLM PM Code list	Principal Meridian Code
PRINMER	String	40	Principal meridian name as a text	Principal Meridian Text
TWNSHPNO	String	3	Township number. The Township Number indicates the number of rows of townships, north or south from a Public Land Survey System Origin.	Township Number
TWNSHPFRAC	String	1	Township fraction. Township Fractions are created when there are gaps between surveyed Township boundaries or due to excess size in Townships that arose from executing original surveys.	Township Fraction
TWNSHPDIR	String	1	Township direction. The direction of a row of Townships from a Public Land Survey System Origin. These are typically North and South in the West but may be East and West in Ohio	Township Direction
RANGENO	String	3	Range number. The Range Number indicates the number of columns of townships, east or west from a Public Land Survey System Origin.	Range Number
RANGEFRAC	String	1	Range fraction. Range Fractions are created when there are gaps between surveyed Township boundaries or due to excess size in Townships that arose from executing original surveys.	Range Fraction
RANGEDIR	String	1	Range direction. The direction of a column of townships from a Public Land Survey System Origin. These are typically East or West in the west but may be north or south in Ohio	Range Direction
TWNSHPDPCD	String	1	If there are multiple townships in a Public Land Survey System Origin, State and Survey Name, the Township Duplicate Status is used to establish uniqueness. When more than one Public Land Survey System Township has the same Township and Range numbers and directions and fractions, and is in the same State, this attribute is used to distinguish among duplicate values.  A is the first duplicate, B the second etc.  A 0 in this field indicates no duplicates	Township Duplicate
PLSSID	String	50	Concatenation of the principal meridian, township, range, and duplication code that form a unique id.	Township Identifier
TWNSHPLAB	String	20	Township label that is used for cartographic output or web display	Township Label
SRVNAME	String	60	A common or otherwise recognized name for a portion of area of a PLSS Survey, for example the refugee lands in Ohio or in cases where a PLSS Township has a recognized name.	Survey Name for PLSS Areas
SURVTYP	String	2	Code of the type of special survey, typically these are the codes described in the BLM data collection as survey type codes	Survey Type Code
SURVTYPTXT	String	50	Special survey type text description, for interpreting the codes	Survey Type Text
SOURCEDATE	Date	8	The date of the source document	Source Date
SOURCEREF	String	100	The reference to the source document could be a reference to a map or plat or a deed. This could include document type.	Source Doc Link or Reference

Why is the state included in the PLSS Township Table?  This is because in some cases, notably along the Colorado-Kansas boundary, the Principal Meridian, numbers and directions for two “columns” of townships are repeated, with the only unique designation being the state.  Also many state boundaries in the west are coincident with Township boundaries.  Townships that are split by state lines are divided into two polygons for the standardized data.

The survey type is used to identify unsurveyed townships and townships that have been defined on a protraction diagram, which is a plan of survey.  If the survey type is blank, the township boundary has been surveyed.  The source date and source reference are optional fields that can be used to identify the first date of survey and the source document, typically a General Land Office (GLO) or BLM plat.

The figure below illustrates some fractional or half township and half ranges in Nevada. Fractional parts can be half, quarter, or three quarters.  Fractional townships may not be familiar to many of the PLSS data users, but they occur in almost every state.

The other exceptional coding are the duplicate townships.  This happens when the Township tier, range, and PM are duplicated within a state.

The image below is from a portion of the Ohio PLSS from the Ohio River Base PM.  The Township labels have the duplicate code at the end.  The first duplicate has an A indicating that another Township with the same designation exists.  The convention is to assign the first duplicate code, A, to the township closest to the baseline or PM.

The Principal Meridians included in the PLSS CadNSDI standardized data are listed.

Principal Meridians

Principal Meridian Code	Principal Meridian Description
01	1st Meridian
02	2nd Meridian
03	3rd Meridian
04	4th Meridian
05	5th Meridian
06	6th Meridian
07	Black Hills Meridian
08	Boise Meridian
09	Chickasaw Meridian
10	Choctaw Meridian
11	Cimarron Meridian
12	Copper River Meridian
13	Fairbanks Meridian
14	Gila-Salt River Meridian
15	Humboldt Meridian
16	Huntsville Meridian
17	Indian Meridian
18	Louisiana Meridian
19	Michigan Meridian
20	Montana Meridian
21	Mount Diablo Meridian
22	Navajo Meridian
23	New Mexico Meridian
24	St. Helena Meridian
25	St. Stephens Meridian
26	Salt Lake Meridian
27	San Bernardino Meridian
28	Seward Meridian
29	Tallahassee Meridian
30	Uintah Meridian
31	Ute Meridian
32	Washington Meridian
33	Willamette Meridian
34	Wind River Meridian
36	Between the Miamis
37	Muskingum River
38	Ohio River Base
44	Kateel River Meridian
45	Umiat Meridian
46	Extended Fourth Meridian
47	West of the Great Miami
48	Base Line of the US Military Survey
99	Not Applicable