The report gives results of the demonstration of a new methodology for developing a combustion source fuel use and emissions inventory. The demonstration area encompassed 150 counties within a 200 mi (320-km) radius of the Adirondack Mountains in New York State, believed to be representative of the Northeastern U.S. A complete combustion inventory of nitrogen oxides (NOx) emissions was developed for the 150 counties. All sectors (residential, commercial, transportation, utility, and industrial) were included. In the industrial sector, the methodology entailed: (1) identifying all major combustion processes and associated equipment, and (2) developing NOx emission factors. This approach produced a list of 28 facilities and 73 processes, believed to include all significant combustion sources in the 150-county area. An approach was also developed for treating all fuel consumption not accounted for by installations that include major combustion processes. The latter block of fuel consumption was translated into 'residual' industrial area source NOx emissions. As intended, the project demonstrated fully the essential elements of a methodology that would allow development of a county-by-county NOx inventory for all fuel burning in all or any part of the U.S., without resorting to user surveys or inventories based on such surveys.