Between the War Years

1919-1939 marks the years between the two major wars of the twentieth century.  Although a short period of time, history saw the boom of the 20s, the bust of the 30s, the rise of totalitarian rulers and the fall of traditional governments.  Technology changed transportation, communication, entertainment and society's overall way of life.  In your opinion, what was a significant event from this time period that has impacted our society to this day?  Explain briefly.