U. S. Geological Survey study. Six assessment areas; based on generally distinct geologic characteristics. Study focused on source beds and thermal maturation, reservoir rocks, structural and stratigraphic traps, and seals and timing of hydrocarbon migration relative to formation of traps. Individual assessment areas appear to have the most attractive petroleum potential in the following order: Perdido Foldbelt, Sigsbee Knolls, Abyssal Gulf Basin, Campeche Escarpment, Rio Grande Margin, and Sigsbee Escarpment. Estimates of the amount of petroleum resources ultimately recoverable were not calculated.M-Modified journal abstract.