The GIS Data Inventory (Inventory) contains a list of Federal and state resources and geospatial data that can be used to inform the National Environmental Policy Act (NEPA) review and other environmental review and authorization processes. The environmental- and NEPA-based geospatial data presented in the Inventory were identified through an online survey, focus groups, and interviews with Federal agencies, and are available as both downloadable data as well as published web services. The Inventory also includes some state-level data as a resource for environmental compliance, and includes each state's site, portal, and/or web services websites. The Inventory is not comprehensive and may be updated with additional resources and data as they are identified. This list supplements but does not take the place of agency coordination with entities that manage relevant information for environmental reviews.