Fuel loadings, from canopy to litter and duff, are key variables for informing wildland fire emissions inventories. At regional to national scales, fuel loadings and their spatial patterns vary in both space and time, but current geospatial fuel datasets do not account for this variability, making inventories of smoke and emissions challenging, hard to replicate, and difficult to defend both scientifically and for their diverse applications to policy and management. We propose to develop maps of fuels for the Contiguous United States (CONUS) and Alaska (AK) that will incorporate their variability and enable an accurate quantitative accounting of fire emissions with a realistic assessment of uncertainty. The goal is to develop fuels mapping products for national- and regional-scale modeling of emissions. We accomplish this by assigning each component of a fuel type (e.g., FCCS fuelbed) a characteristic range of variation that accounts for variability of fuel loadings in space and time computed from high-quality field-based datasets available from extensive field sampling over the past 20 years. The project has three objectives: (1) Develop methods to map and validate wildland fuel loadings for emissions modeling that incorporate spatial and temporal variation at multiple scales; (2) create and distribute geospatial fuels and emissions products for regional and national smoke management and emissions inventories; and (3) evaluate sources of uncertainty and data gaps for emissions estimates using a sensitivity analysis of emissions models to fuel variability informed by distributions of fuel characteristics. These tasks include tapping the large set of data used in developing the FCCS fuelbeds and other field data to characterize fuel loadings statistically for each fuelbed stratum. Fuel loadings distributions can then be exploited to employ fuel loadings in modeling fire emissions in a quantitative and statistically rigorous method. Two sub-tasks planned are to: (1b) demonstrate map validation at three geographic locations in CONUS and AK using existing field data collected in accordance with validation methodology requirements; and (2b) develop a web-based system to access, map, and use the database and information on fuel loadings created in the proposed project. The project deliverables include a geospatial database of fuel loading distributions; software to manipulate and display its contents; sample outputs and guidance on how to use the database; and reports on results of the sensitivity analysis and validation methods, successes, and challenges. Our project results will be presented through journal publications, symposium papers, and a webinar to be facilitated by JFSP regional consortia to inform the user community about project outcomes and datasets and tools valuable for emissions modeling.