"Hold your tongue, the job is not done", Hawley Plant security poster, Milwaukee, 1943...

Sister Manhattan Project site billboard, Similar security signs were also posted at the secret site in Los Alamos during World War II. All of these secret towns were secretly competing against other facilities that sprung up at the same time in the race to successfully to make an atomic weapon, Artist: Allis Chalmers, Milwaukee, Wisconsin The town of Oak Ridge was established by the Army Corps of Engineers as part of the Clinton Engineer Works in 1942 on isolated farm land as part of the Manhattan Project. The site was chosen for the X-10 Graphite Reactor, used to show that plutonium can be extracted from enriched uranium.