After World War II began to give way to the Cold War, the United States pursued nuclear supremacy through extensive weapons testing by Edward Teller and the Atomic Energy Commission, which detonated hundreds of devices underwater, underground, and in the atmosphere. Although weapons development remained the main priority, the Atomic Energy Commission also sought peaceful uses for atomic power through Operation Plowshare, an experimental program launched in 1957 by California's Lawrence Livermore Laboratory for applications including power plants, medicine, mining, oil and natural gas extraction, and the excavation of canals, harbors, and roadways. In 1963, Project Carryall emerged from this effort as a feasibility study to realign the Atchison, Topeka and Santa Fe Railroad and provide a route for Interstate 40 by using 23 nuclear explosions totaling 1.8 megatons to excavate a one-half-mile cut up to 350 feet deep through the Bristol Mountains east of Ludlow and remove 60 million cubic yards of rock. Despite repeated assurances of safety from the Atomic Energy Commission, environmental and health concerns over this and other Operation Plowshare proposals led to several postponements, and the project was abandoned in 1968; 28 nuclear tests were conducted under Operation Plowshare before the program ended in 1975.