The Roaring Twenties is the name given to a very important decade in American history. This was a period in which many of the old certainties were undermined by huge changes in society and the economy. During this pivotal decade in American history, many of the old social values were challenged as technological developments such as the automobile and the cinema gave many Americans, especially the young, a newfound sense of freedom.
At the same time, paradoxically, the United States became more puritanical in some respects. This was the decade in which Prohibition reigned, in which Protestant fundamentalists found a new voice which they used to decry what they saw as increasingly godless elements in society, such as the "immoral" movie industry and the teaching of evolution in public schools. To some extent, this was a backlash against sudden changes in society brought about by the rapid development of the US economy.
During this decade, public opinion became increasingly tilted toward isolationism, the belief that America should stay out of other countries' affairs and leave them to sort out their own problems. Allied to this was a strain of ugly nativism which saw mass immigration to the United States as a threat to so-called 100% pure Americanism. It's no surprise that the Ku Klux Klan achieved the pinnacle of its political power in the United States during this decade as more and more white Protestants took fright at what they saw as the undermining of traditional American values by the influx of newcomers.