- It was war that caused that.
During this time, there was high worldwide economic growth; Western European and East Asian countries in particular experienced unusually high and sustained growth, together with full employment.
Contrary to early predictions, this high growth also included many countries that had been devastated by the war, such as Japan (Japanese post-war economic miracle), West Germany (Wirtschaftswunder), France (Trente Glorieuses), Italy (Italian economic miracle), and Greece (Greek economic miracle).
The period from the end of World War II to the early 1970s was a golden era of American capitalism. $200 billion in war bonds matured, and the G.I. Bill financed a well-educated work force.
The middle class swelled, as did GDP and productivity. The US underwent its own golden age of economic growth. This growth was distributed fairly evenly across the economic classes, which some attribute to the strength of labor unions in this period -- labor union membership peaked during the 1950s.
Much of the growth came from the movement of low-income farm workers into better-paying jobs in the towns and cities -- a process largely completed by 1960.
Government programs of bonds and education, labor unions, full employment in war devastated countries, fair progressive taxation, a growing middle class rather than a shrinking one that has occured since top rates were lowered....
It's like you need to be deprogrammed.