Based on satellite imagery taken in 2001, the broad, yet precise database was constructed in a six year collaborative effort by the 11 MLRC agencies. NLCD 2001 products include 21 classes of Land Cover, Percent Tree Canopy and Percent Urban Imperviousness at 30 m cell resolution. Currently, products are available for the conterminous United States, with Alaska, Hawaii, and Puerto Rico planned to be available by December of 2007. The 76 standard NLCD mapping zones (including Alaska) have been grouped into 17 larger zonal areas for easier distribution and download. See www.mrlc.gov
