The 1920's was a time of Prohibition and apparent prosperity in America (certainly not in Europe).  The era of flappers, speakeasies and the Tommy Gun represent an era of denial in American History.  It's almost like the country wanted to put the war years behind them let the good times roll.  The end of the Roaring 20's brought with it economic depression, a brutal drought in the midwest and a president (Franklin Delano Roosevelt) with a new vision with regard to the role of government in the 20th Century.  Like in the early part of the century, America did not look far beyond its borders.  But like the days before WWI, events taking shape around the world were destined to impact America in profound ways when World War II erupted.