Data Layer: PUBLIC LAND SURVEY SYSTEM: PLSS (DLG)
You are invited to read the definitions of terms used in this data standard.
||Public Land Survey System (PLSS) Data (DLG)|
||The data consists of digital maps created by the U.S. Geological Survey (USGS) that depict public survey information, such as township, range, or section locations, referred to in legal land ownership descriptions in the United States. Although these data now exist in Spatial Data Transfer Standard (SDTS), as well as Digital Line Graph (DLG) format, they are still called DLG data. The data are available on the Internet, free-of-charge, or on inexpensive CD's. The CD's contain 1:100,000- and 1:2,000,000-scale data in DLG format, available nationally. The 1:24,000-scale data on the Internet is available only in SDTS format. While it is not yet completed nationally, work is in progress.|
||USGS EROS Data Center is the source for 1:100,000-scale data in DLG format.
SDTS information for USGS data available in SDTS format.
|Historical Data||For information on past versions of this standard, contact the National Data Administrator, Branch of Data and Systems Services, Division of Information Resources and Technology Management.|
Part 270, FW 6, Data Management and Standards, has been superceded by Part 274, FW 2, Establishing Service Data Standards.
USGS DLG Data - product description, prices, sample data, search and order DLG data.
DLG Standards - this site includes links to DLG documentation, selectable by scale at the site; very large documents.
The SDTS Information Site - includes documentation, FAQ's, and data pointers.
||The USGS PLSS data layer in DLG format should be used wherever it is available in an
appropriate scale, with current information, and particularly if users need the attribute
information associated with the polygon coverage. Alternative data may be needed if the
USGS data is old or not in the large-scale format.
In particular, the Geographic Coordinate Data Base (GCDB) data from the Bureau of Land Management (BLM) for 17 western states may be more accurate as a line coverage. This would be important in determining boundary information for refuges or other applications where line accuracy is an over-riding factor. The GCDB data, however, does not have the attribute information that the PLSS coverages do. There may be times when both coverages are needed. There is an ongoing discussion between USGS and BLM about merging the data; this data standard and the related tools will be updated as needed.
Note: When using the GCDB data, the PLSS data, or any other data source for applications where accuracy is a major issue (such as determining boundary information), you need to carefully check documentation on the source of the data. Quality will vary widely based on the source materials available or used; each state had the option to create the GCDB data differently.
Limitations: Data should always be used at the scale appropriate to the application. The USGS makes every effort to achieve a high level of accuracy in all of its published products. An important aim of its accuracy control program is to meet the U.S. National Map Accuracy Standards. These standards vary with scale; for example, 1:24,000-scale data will be much more spatially accurate than data at the 1:100,000-scale. If the degree of precision is very important to the application, check the above reference to make sure the data being used are appropriate.
Visit the Public Domain Software for Use with USGS Geographic Data page for notes on all DLG data.
||January 14, 1999|
||January 28, 2011|
||Chris Lett, National FWS GIS Coordinator, Branch of Data and System Services, Division of Information Resources and Technology Management.|