One bomb eliminated nearly all structures.

On August 6, Hiroshima was the first city devastated by an atomic bomb. In a single blast that lasted just less than three seconds, a five square mile area of the city was destroyed. That is 60,000 of the city’s 90,000 buildings.  The immediate toll in lives was 80,000 either killed instantly or seriously wounded. Between 90,000 and 166,000 dies in the months that followed.

On August 9, the city of Nagasaki became the second city destroyed by an atomic bomb. On the day of the bombing, an estimated 263,000 people were in Nagasaki along with 9,000 Japanese soldiers, and 400 prisoners of war.  Of these people between 40,000 and 75,000 people died immediately, while another 60,000 people suffered severe injuries. 

The death toll was higher than in the one-time assault on the city of Tokyo. On August 15, an estimated 100,000 died, and 10 square miles of the city containing 250,000 buildings were destroyed.