This coverage contains estimates of nitrogen-fertilizer sales for the conterminous United States in 1990 as reported by the U.S. Environmental Protection Agency (1990) and by Jerald Fletcher (West Virginia University, written commun., 1992). Nitrogen-fertilizer sales estimates in this coverage are reported for each county polygon in tons of actual nutrient sold (inorganic nitrogen, phosphate, and potash) as distinct from total tons of fertilizer product. The data are summarized for fertilizer years (i.e. the 1987 fertilizer year runs from July 1, 1986 to June 30, 1987). The polygons representing county boundaries in the conterminous United States, as well as lakes, estuaries, and other nonland-area features were derived from the Digital Line Graph (DLG) file representing the 1:2,000,000-scale map in the National Atlas of the United States (1970). Nitrogen-fertilizer Commercial fertilizer Fertilizer use Counties United States