MAP ACTIVITYMap 30.2 Worldwide Oil Reserves, 1980 Geologists and engineers can estimate the size of “proved oil reserves,” quantities recoverable with existing technology and prices. In 1980, worldwide reserves were estimated at 645 billion barrels. Recovery of reserves depends on many factors, including the location of the oil. Large portions of U.S. reserves, for example, lie under the Gulf of Mexico, where it is expensive to drill and where hurricanes can disrupt operations.READING THE MAP: Where did the United States rank in 1980 in the possession of oil reserves? About what portion of the total oil reserves were located in the Middle East?CONNECTIONS: When during the 1970s did the United States experience oil shortages? What caused these shortages?