How is The Great Gatsby a commentary on the decay of social and moral values that came about in the 1920s?

The novel parallels the context of society during that time, which creates a backdrop of realism that serves to emphasize the social and moral decay of the 1920s. During the time in which the novel was written in, the 18th Amendment was passed and it outlawed the "manufacture, sale, or transportation of intoxicating liquors" on a national level. Prohibition, however, had little effect on the hedonism of the liquor-loving public, and speakeasies, a type of illegal bar, cropped up everywhere.

In the Great Gatsby, many, such as the protagonist Gatsby, took advantage of the 18th amendment and opened up a lot of “side-street drug-stores”, that “sold grain alcohol over the counter”, confirming Tom’s suspicion in chapter 6 that “A lot of these newly rich people are just big bootleggers”.

Additionally, Gatsby also has other stores in other states such as “Chicago” and “Philadelphia” that were “calling him on the wire”.

There is also the use of synecdoche, “Chicago” and “Philadelphia” to represent Gatsby’s illegal activities in other states also serves to highlight the immoral activities that have spread throughout America like a plague. Ultimately, highlighting the decay of social and moral values that came about in the 1920s as people used whatever means they could to attain wealth.

Fitzgerald portrays the decay of social and moral values during the 1920s by illustrating the opulence, greed, deceit, and reckless behavior of the wealthy citizens living in New York City and Long Island. Fitzgerald is highly critical of American citizens' unrestrained desire for status, wealth, and pleasure during the 1920s, which is most significantly depicted during Gatsby's wild parties. Fitzgerald's poignant commentary of the reckless social atmosphere of the 1920s also depicts the corruption and vain pursuit of the American Dream. Essentially, Jay Gatsby reaches the apex of American society through illegal means only to feel empty and lonely. The same can be said for Daisy Buchanan, who marries Tom simply because he is wealthy but suffers in her terrible marriage. Fitzgerald also portrays the hypocrisy of society by illustrating how the most wealthy, physically attractive people are morally debased. Despite Daisy's outward beauty, she is extremely superficial, careless, and shallow. Overall, Fitzgerald illustrates the dark side of the Roaring Twenties by depicting the vain pursuit of the American Dream, emphasizing the corrupting effects of materialism, and portraying the consequences attached to leading a life full of debauchery and pleasure.