What were the fundamental causes of the spectacular prosperity of the untied states in the decades immediately after world war ii?

New technology--new and updated automobiles and appliances, television sets.

Large amount of new families--this caused a boom in housing needs and with a baby boom, a large number of consumer products for babies and eventually children and teenagers emerged. 

A belief in capitalism to combat communism--citizens were encouraged to buy and invest in the capitalistic system. 

Wage increases and ability to spend--for the first time since the 1920s, the population had money and the means to spend on themselves and their families.