Jurisdiction in Offshore Submerged Lands and the Significance of the Truman Proclamation in Postwar U.S. Foreign Policy

In September 1945, with a Proclamation issued in the manner of an imperial fiat, President Harry S. Truman claimed “jurisdiction and control” over the subsoil resources of the continental shelf.1 This expansionist act differed from better known moments of U.S. territorial imperialism as the land involved was on the offshore continental shelf and submerged entirely underwater. The scale of the submerged land claims should not be underestimated. This offshore territory now declared to be “appertaining to the United States” covered an area nearly the size of the Louisiana Purchase, and contained mineral wealth of potentially even greater value. In a phrasing it reused in multiple documents, the U.S. Geologic Survey (USGS) recognized that “by that act the equivalent of a new continent was thrown open for geological exploration and mineral exploitation. The continental shelves of the United States and its possessions comprise roughly a million square miles—four times the area of Texas, or one-third of the area of continental United States.”2 Without a doubt, “this opened a tremendous area for exploration and development by the United States and its citizens.” A 1945 federal estimate of the total area of the continental shelf ran as high as 908,000 square miles, though the more commonly cited figure at the time was 760,000 square miles.3 The land area of the entire continental United States is 2,954,841 square miles. The offshore territory was expected to have at least three percent of the proven oil reserves of the United States, as well as sulphur, magnesium, bromine, ilmenite, rutile, ziricon, chromite, and other minerals.4 Whatever the exact extent and nature of the submerged territory, the United States sought to define, control, exploit, and govern this space.

Archaeology · Continental shelf · Expansionism · Geography · Jurisdiction · Political science · Politics · Proclamation · Square (algebra) · Submarine pipeline · Geology · International Maritime Law Issues · Law · Oceanography · Space exploration and regulation

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