In 1967 Congress passed an amendment to the Clean Air Act of 1963 that provided for an intergovernmental system for the abatement, prevention and control of air pollution on a regional basis. The role of the Federal Government is to provide leadership. Implementation is the primary responsibility of state and local governments. Criteria and control technology guidelines have been published for sulfur oxides, particulate matter, hydrocarbons, carbon monoxide, photochemical oxidants, and nitrogen oxides. The report contains maps and data describing the air quality control regions presently designated through the 50 states, District of Columbia, Guam, American Samoa, Puerto Rico and the Virgin Islands.