In 1942, more than 15,000 people came to work and live at Clinton Engineer Works (The Secret City), a massive industrial complex nestled in the hills of what would become Oak Ridge, Tennessee. Here, men and women worked on enriching uranium for the Little Boy bomb. The combined employment peak (production staff, operating force, and construction labor) was 80,000. Today The American Museum of Science and Energy provides bus tours to this Smithsonian Affiliated site.
The poster is based on a photograph by, Ed Westcott, the official photographer for the Manhattan Project during WWII. The public domain image shows a worker at a calutron in Y-12 where uranium was extracted. - Reenie Mooney