Why were the 1920 called the roaring 20s?

The 1920's were called the Roaring Twenties because it was a period of extreme power and happiness in America. Skirts got smaller and smaller which shocked the older generations and Jazz had developed and spread. Automobile's rolled down the streets and the US was strong and influential in the world. This period ended in the 1930's when the Stock Market crashed plunging the US in the Great Depression.