National Land Cover Data (NLCD)
One of the projects sponsored by the MRLC consortium was production of
land-cover data derived from images acquired by Landsat's Thematic Mapper
(TM) sensor, as well as a number of ancillary data sources. The NLCD includes
the source images, as well as classified land-cover data for specific
acquisition dates. It is the first national land-cover data set produced
since the early 1970s, effectively replacing the LUDA and GIRAS data sets.
Data for the conterminous United States circa 1992 (1992
NLCD)  , which were derived from Landsat-5 TM images are complete and
currently available for download. Description of the data, as well as
the classification process utilized have been published in a number of
journal articles.
Currently, the entire United States is being mapped using imagery acquired
circa 2000 (2000
NLCD)
from Landsat-7's enhanced TM (ETM). This project entails re-mapping the
lower 48 states, as well as covering Hawaii and Alaska for the first time.
Classification schemes
for the two rounds of classification are similar, but not identical.
Accuracy of the 1992 NLCD is available and reported by EPA federal region.
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