Through the Western States Air Resources Council (WESTAR) – WESTAR and WRAP, the Central States Air Resource Agencies (CenSARA), the Mid-Atlantic Regional Air Management Association (MARAMA) and the Lake Michigan Air Directors Consortium (LADCO) organizations have contracted with Ramboll Environ to perform an analysis of the national upstream and midstream oil and gas (O&G) emission inventory in Task 1, and then moving to 5 Regional Basin-specific analyses in Task 2. The project will review the data available in the various portions of the 2014 national inventory, its representativeness and completeness, as well as then also performing more detailed basin-level analyses to provide insight into O&G inventory inputs and emissions for selected basins. The project will result in prioritized recommendations of which input data sources could be improved to enhance inventory accuracy. The project is receiving in-kind support from U.S. EPA and review by the members of the National Oil & Gas Emissions Committee; results from this project will also be maintained as part of the resources available on the National Oil & Gas Emissions Committee Information Repository.