Changes in nutrient inputs, cycling, and management within the contributing watershed can be key drivers of nutrient delivery to sensitive coastal waters, such as the Gulf. We analyzed new, basin-wide nutrient input, crop removal, agricultural surplus, and nutrient use efficiency (NUE) metrics to support nutrient reduction goals and assess the collective impact of nutrient management across the Mississippi/Atchafalaya River Basin (MARB). Agricultural surplus is the sum of agricultural inputs minus crop harvest and NUE is crop harvest divided by the sum of N or P sources. This analysis leveraged EPA’s National Nutrient Inventory (NNI), which assembles N and P inputs at the county, state, HUC8, and HUC12 scales. County level NNI data were apportioned to the MARB subbasin level using a dasymetric allocation approach based on the National Land Cover Dataset (NLCD). For each of the six MARB subbasins (HUC2), we used these apportioned metrics to calculate agricultural surplus and nutrient use efficiency. Agricultural inputs account for more than 80% of N and P inputs to the MARB watershed. For the entire MARB, from 1987-2017, agricultural N and P inputs have increased by 46% and 32%, respectively, which have been offset by a 66% and 71% increase in crop removal for N and P, respectively. Although N and P agricultural inputs increased across the MARB, crop N and P nutrient use efficiencies increased by 6% and 15% in tandem, resulting in stable agricultural N surplus and declining agricultural P surplus. These trends may indicate progress toward reducing nutrients available for export across the basin. Current goals include making watershed-level NNI data accessible in EPA’s StreamCat and LakeCat databases and connecting nutrient inputs to measurements of MARB water quality.