A 1945 Life article estimated that before the Hiroshima and Nagasaki bombings "probably no more than a few dozen men in the entire country knew the full meaning of the Manhattan Project, and perhaps only a thousand others even were aware that work on atoms was involved."
En opgørelse fra 1945 vurderede imidlertid, at "formentlig kun nogle få dusin i hele landet kendte hele betydningen af Manhattanprojektet, og måske kun 1000 andre var klar over, at det handlede om arbejde med atomer."