National Land Cover Dataset
Note: Other land cover data options are listed on the Land Use/Land Cover Data webpage.
The Original National Land Cover Dataset was created in 1992 by the Multi-Resolution Land Characteristics (MRLC) Consortium. 2001, 2006, and 2011 National Land Cover Dataset releases have followed, and are complete nationwide.
Product description from USGS: "Derived from the early to mid-1990s Landsat Thematic Mapper satellite data, the National Land Cover Data (NLCD) is a 21-class land cover classification scheme applied consistently over the United States. The spatial resolution of the data is 30 meters and mapped in the Albers Conic Equal Area projection, NAD 83."
Processing overview from USGS: "The TM multi-band mosaics were processed using an unsupervised clustering algorithm. Both leaves-off and leaves-on data sets were analyzed. The resulting clusters were then labeled using aerial photography and ground observations. Clusters that represented more than one land cover category were also identified and, using various ancillary data sets, models developed to split the confused clusters into the correct land cover categories."
The 20-class National Land Cover Data Key for 2011 data may be found online at: https://www.mrlc.gov/nlcd11_leg.php
Background from USGS: "The National Land Cover Characterization project is part of the interagency Multi-Resolution Land Characterization (MRLC) initiative involving three divisions of the US Geological Survey (National Mapping Division, Water Resources Division, and the Biological Resources Division), the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, and the US Forest Service. These agencies have a requirement for a nationally consistent land cover data set, and in 1993 these agencies combined financial resources to purchase Landsat Thematic Mapper data covering the entire United States. The USGS/EROS Data Center took the lead to process the data and develop the National Land Cover Data (NLCD) set. Procedures to evaluate the accuracy of the final product have been developed, and private contractors are completing accuracy assessments."
The 2011, 2006, 2001, and 1992 NLCD data and further documentation are available from numerous online sources. These include:
- USGS National Map Viewer
- Multi-Resolution Land Characteristics (MRLC) Consortium
- USGS Land Cover Institute
Note: With each new data release, the USGS has been also releasing updated versions of previous year's data. For the 2011 release, the following note is on the top of the page: "NLCD 2001 (2011 Edition) and NLCD 2006 (2011 Edition) products must be used in any comparison of NLCD 2001, NLCD 2006 and NLCD 2011 data products." They also note the following regarding 1992 data: "NLCD 1992 is not recommended for direct comparisons with any subsequent NLCD data products (i.e. NLCD 2001, NLCD 2006, NLCD 2011). The typical result of direct comparison will result in a change map showing differences between legends and mapping methods rather than real changes on the ground."
Derivative products have also been created from the data - For example, from 2011 there are various Change Detection, Tree Canopy, and Imperviousness rasters provided from the MRLC.
NCSU Data Access
NORTH CAROLINA: 2011, 2006, 2001, and 1992 North Carolina data are available on the Geodata Server under /fedgov/usgs/landcov with accompanying metadata and layer files. On campus link Off campus link
Each of these are ArcInfo GRIDs, clipped to NC boundaries, and projected to NC Stateplane NAD83 Meters, as shown in the graphic at the top of this page.
See the GIS Lookup Detailed Data Record for the 2001 data.
1992 data for other eastern U.S. states is available on CD-ROM (G3701 .A4 1992 .G46) in the GIS Cabinet, DH Hill Reference Area. Data can also be made available for FTP upon request to Data Services. The following image shows data organization by CD-ROM: