The Environmental Management Technical Center's (EMTC) Fiscal Year 1992 effort to develop a systemic spatial data base of land cover/land use within the Upper Mississippi River System (UMRS) has been completed. The UMRS spans eight degrees of latitude and includes the Upper Mississippi River from Minneapolis, Minnesota, to Cairo, Illinois (130 km), and the navigable reaches of the Illinois (526 km), the Kaskaskia (19 km), the Black (2 km), the St. Croix (40 km), and the Minnesota Rivers (42 km). Systemically, the aerial extent of the study area includes 1,137,035 ha (2,809,575 a) as defined by the floodplain of these river reaches. The EMTC acquired and processed 1989 Landsat Thematic Mapper (TM) satellite imagery to produce the land cover/land use data base. The Landsat program, which began in 1972 with the launch of the first multispectral scanner by the National Aeronautics and Space Administration, has evolved over time and now provides much higher spatial and spectral resolution than earlier platforms. Each scene recorded covers an area on the ground approximately 185 x 170 km and has a pixel resolution of 30 x 30 m. Seven full scenes were required to cover the study area, from which the floodplain was extracted. Figure 1 displays the study area and the coverage of each scene. Image processing was accomplished using the Earth Resources Data Analysis System. Once the data are edited they will be converted to the ARC/INFO GRID module for analysis.