In 1920s America gained the policy of isolationsim - being independent and not getting into the wars in Europe or any other conflicts, focusing on your own countires and its own interest.
The boom, in theory, meant:
-money for education/ investigation - industrial progress ( trippled)
-more jobs -new goods produced
-less crime/ imigrants - new roads bilt/ cars manufactured
-business are doing well
-the satisfactional life
-better quality of life
-change of morality
- The quality of living was much higher than in it was in Europe after the WW1.
- Travelling became easier.