Continental Shelf Expansion: The US Interior Department’s Quest for Oil, 1945–69

In early 1946, outgoing Secretary of the Interior Harold Ickes was giddy at the opening of one of America’s “new frontiers”: the continental shelf, to which President Harry S. Truman had recently laid claim. Ickes celebrated the sheer magnitude of the annexation, which was one-fifth the size of the nation and nearly the size of the Louisiana Purchase. Though uninhabitable, Ickes observed, the underwater expanse was rich with untold oil potential. While historians have acknowledged the importance of the oceans to American expansionism in the context of trade and navigation, they have largely overlooked how the nation’s entrance into the continental shelf itself marked an expansion that was, in Ickes’ words, “of historical significance.” As American officials and allied oil corporations confronted difficulties accessing minerals abroad in decolonizing countries in the 1950s and 1960s, they increasingly turned to zones closer to home, including offshore. The incorporation of the continental shelf had a colossal role to play in U.S. energy security.

The U.S. Interior Department brought in this mineral-rich terrain. In the Second World War, the Interior Department had become a clearinghouse of energy resource expertise. Yet Interior also was the longstanding home of conservationism and the new hub for environmental protection. Despite the apparent environmentalism of the department, Interior became a key driver in a frenzied offshore oil land grab. Leaders like Stewart Udall spearheaded the sale of $1.5 billion in revenues from offshore leases, which would fatefully lead, in just one year’s time, to the Santa Barbara oil spill—the largest the world had seen. In this way, Interior’s push for economic development of energy resources cut against environmental and social wellbeing of the nation and the world.