The National Historical Geographic Information System (NHGIS) summary data files provide environmental data from the National Land Cover Database (NLCD). NHGIS and Social Explorer tables include computed 2001, 2006 and 2011 land cover summaries for 2000, 2010 and 2015 states, counties and census tracts. U.S. Environmental Summaries is a category of data layers within the Social Explorer application. To find individual datasets, log in to Social Explorer, select a category, and browse to the desired layer.Website999-0001-018engSocial Explorer8888-001RestrictedCensusSocial Explorer: U.S. Environmental SummariesDatasetsUnited States