American concerns over air defense of the continental United States were at their most grave in the 1950's. The descent into cold war in the late 1940's, the confrontation of two hostile political systems in distant Korea, and the Soviet development of atomic weapons earlier than expected came together to stimulate popular pressures for a shield against manned bombers reaching the American heartland from the North Pole. This manuscript describes the efforts take by the Air Force in light of the real threats of nuclear weapons. The postwar Air Defense Command, an administrative and planning backwater compared to the Strategic Air Defense suddenly assumes far greater significance, absorbing a larger portion of the defense budget. The expansion of air defense forced the Air Force to consider issues it has not addressed in the past including guided missile defense, continental implications, and international political issues.