How many cities in japan did the united states drop an atomic bomb on in 1945?

Two

The cities were Hiroshima and Nagasaki. On August 6, 1945, a bomb was dropped on Hiroshima that instantly killed around 80,000 people, and many thousands more from after-effects of the nuclear explosion. On August 9, 1945, a second atomic bomb was dropped on Nagasaki, with an immediate death toll of around 40,000.