In the year 2055 a nuclear arms race broke out between the U.S. and Great Britain. The NATO treaty had been broken several times by each country and war was on the verge of breaking out between them. Italy, France, and Germany took the side of Great Britain and Canada, Iceland, and Spain took the side of the U.S. The rest of the countries simply decided it was best to stay out of this soon to be war. In 2060 America bombed Northern Ireland to nothingness. World War 3 had begun.
Canada was hit hardest during the beginning of the war and had its population nearly cut in half by the time it pulled out. The U.S. and Spain launched a combined attack against The British Isles after this in an attempt to cause enough damage to win. The United States, now in control of almost all nuclear weaponry brought out the big guns. The U.S. had developed a nuclear atomic bomb 5 times the strength of that of Fat Man, the one dropped on Nagasaki in world war 2.
It was devastating. Far more than America had hoped, or wanted. The others tried to retaliate but America loomed over them with the threat. The war was going to end in their eyes. But Germany had a secret weapon. It wasn't a big bomb, and it didn't arrive in a plane. One man managed to sneak into the white house with a small but powerful bomb and detonated it, killing everyone inside including the president. This led to the end of the war.
The country was saddened that the white house that had stood there for all those years had been destroyed, and they were also saddened by the presidents death. But the worst was yet to come. The economy was in shambles and the Government was more corrupt than ever. Many thought that is why the bomber got away with it.
The government got rid of the free states and then replaced them with strict districts. All the money was given to the capitol and much of it was kept. The rest of it was spread unfairly through the new districts. The new leader called himself president but the title was not true to its origins. The constitution was forgotten completely and the country became new. The government had the name changed to Panem because The United States no longer had states, only the poor districts and was completely different. It isolated itself from other countries and decided to become self sufficient. No tourists were allowed to enter ever and only did the most wealthy get exports from other countries.
Nothing was the same and the United States never was again, only Panem.