The National Emissions Report summarizes annual cumulative estimates of source emissions of five criteria pollutants: particulates, sulfur oxides, nitrogen oxides, hydrocarbons, and carbon monoxide. Source emissions data are reported to the U. S. Environmental Protection Agency under provisions of Section 110 of the Clean Air Act, as amended 1977, and EPA Regulations, Title 40, Code of Federal Regulations, Part 51.321. Summary data are presented for the nation as a whole, for individual states, and for Air Quality Control Regions and individual interstate portions thereof. The data compilations result from the operations of the National Emissions Data System (NEDS), which functions as a component of the comprehensive EPA air information system--the Aerometric and Emissions Reporting System (AEROS). AEROS is managed by the National Air Data Branch, Monitoring and Data Analysis Division, Office of Air Quality Planning and Standards, U. S. Environmental Protection Agency at Research Triangle Park, North Carolina 27711.