Title: Public Land Survey System (PLSS) Townships and Sections
Originator: Bureau of Land Management
Abstract:
These layers are based on Geographic Coordinate Data Base (GCDB) coordinate data. The locations of Public Land Survey System (PLSS) corners, as represented in geographic coordinate pairs, were derived from a variety of source documents, which include U.S. General Land Office and BLM survey plats/notes, as well as survey data obtained from other U.S. Government agencies, private sector survey firms, and local governments. The attributes assigned to PLSS polygons were taken from the BLM's Legal Land Description (LLD) data set, contained within the Legacy Rehost for the year 2000 (LR2000) automated records system.
The coordinate data was produced by using control stations of known location, with varying degrees of accuracy, from various sources which include but are not limited to; U.S. Geological Survey (USGS) topological quadrangles and other sources, National Geodetic Survey (NGS) and US Coast & Geodetic Survey (USC&GS) Cooperative Base Network (CBN) control, Federal Base Network control (FBN), and Continuous Operating Reference Stations (CORS), and Global Positioning System (GPS) data, which is then analyzed and adjusted in concert with official survey data for any given geographic area.
The Land Survey Information System Data Base (LSIS) data is a useful representation of the geometry and topology of parcels contained within the PLSS, but its application is intended for mapping purposes only. The GCDB data served from LSIS is not a substitute for a legal land survey.
The GCDB Data was created to provide the BLM and its public with a set of geographic foundation data that accurately portrays the locations of PLSS corners. The GCDB data is based on the best and most current survey records available and uses known geographic positions of control stations within the PLSS network. This data is a key component of the Land Survey Information System (LSIS) framework upon which parcel boundary information will be assembled.
The BLM GCDB data is regarded as the best PLSS data available. The alternate source data was collected by other agencies or by BLM using less-sophisticated collection methods. Much of the alternate source data for the Western States was collected by the USDA Forest Service; while most of the alternate source data for the Eastern States came from USDA Risk Management Agency. The BLM alternate source data does not have most section subdivisions (similar to LADESC for the GCDB data). However some alternate source sections have been subdivided automatically by BLM to support BLM case (ownership) data. Additionally, the GCDB and alternate source datasets do not provide a complete, seamless layer. The PLSS data collection is ongoing so there are holes in the data - and there are slivers and overlaps that have not been resolved yet.
Additional information:
The two datasets provided prior to 2016 have done been split into four datasets. This was to allow for Alaska attribute
tables with more supporting information. Section boundaries were generated from geodetic latitude and longitude
coordinate pairs as recorded on BLM's official protraction diagrams of the state of Alaska.
Format: vector areas – ESRI shapefile
Spatial Reference Information: Decimal Degrees, North American Datum 1983
