Answer: Driven by growing consumer demand, as well as the continuing expansion of the military-industrial complex as the Cold War ramped up, the United States reached new heights of prosperity in the years after World War II
Poor working conditions, housing, and sanitation led to many people opting to emigrate. The British at the time controlled a massive empire including America, Canada, South Africa, and Australia and people soon started to move to these countries in search of a new life.
Population Shifts
The 15 million Americans who joined the military — who, that is, became employees of the military — all moved to and between military bases; 11.25 million ended up overseas.