The spatial units of the analysis to derive estimates for COMET-Planner were county-rectified Major Land Resource Areas (Figure 1). Major Land Resource Areas (MLRA) are geographically associated land resource units, defined by the USDA, that have similarities in physiography, climate, soils, biological resources, and land use (USDA-NRCS 2006). In the conterminous (48-state) US, there are 227 individual MLRAs. Within each county-rectified MLRA, the COMET-Planner team developed a unique random point sample of approximately 100 points per broad land use category, with some variation in sample size depending on the size of the MLRA and the density of agricultural land use within the MLRA (Figure 2). In total, we modeled 17,858 cropland points and 16,549 grassland points. For each point, recent land use was determined by extracting land cover from Cropland Data Layers (CDL) for 2009-2015 (USDANASS 1990-2015).