2001. United States. Minerals Management Service. This polygon shapefile shows the official protraction diagram (OPD) and leasing map boundaries for the United States, covering areas of the Outer C... Geological Survey (U.S.).
2004. Instituto Nacional de Estadística, Geografía e Informática (Mexico), Geological Survey (U.S.), and Canada Centre for Remote Sensing. This polygon shapefile shows the approximate extent of marine areas in the Arctic covered by permanent polar ice. The data originated from the Cana... Geological Survey (U.S.).