The Manhattan District Formed

Meantime, in Washington, Vannevar Bush, Director of the Office of Scientific Research and Development, had recommended to President Roosevelt that a special Army Engineer organization be established to take full responsibility for the development of the atomic bomb. During the summer, the Manhattan Engineer District was created, and in September, 1942, Major General L. R. Groves assumed command.

General Leslie R. Groves
General Leslie R. Groves, U.S. Army Corp of Engineers, directed the Manhattan Engineer District, 1942-1946.

The Atomic Energy Commission (AEC), a civilian agency, succeeded the Manhattan Engineer District as the governmental organization to control atomic energy on January 1, 1947. On October 11, 1974, President Gerald Ford signed the bill that abolished the AEC. The research and development portions of the AEC were absorbed into the US. Energy Research and Development Administration (ERDA); the regulatory portions of the AEC were absorbed into the Nuclear Regulatory Commission (NRC). On October 1, 1977, the Energy Research and Development Administration became part of the newly created Department of Energy.