This report summarizes the results of a 3-year study of the oil and gas resources of the onshore and state waters of the United States by the U.S. Geological Survey. A parallel study of the Federal offshore is being conducted by the Minerals Management Service. Estimates are made of technically recoverable oil, including measured (proved) reserves, future additions to reserves in existing fields, and undiscovered resources. Estimates are also made of the technically recoverable conventional resources of natural gas in measured reserves, in anticipated growth of reserves in existing fields, and in undiscovered resources. Additionally, an assessment is made of recoverable resources in continuous-type (largely unconventional) accumulations in sandstones, shales, chalks, and coal beds.