Someone told me you can see based on a character's description if he/she comes from West or East. What is an example?
A great example of this would be Tom Buchanan. When he is first mentioned, Nick remembers him as “one of the most powerful ends that ever played football” at Yale. From that first moment, we know he's strong and powerful. He must also be able to push others around if he plays as an end on the line in football. We see immediately how he has control over George when he takes Nick with him to meet Myrtle. He is able to easily push him around, and he gets what he wants out of Myrtle. When she mentions Daisy's name when they're at "her apartment," Tom hits her--hard enough to bloody her up. These are examples of his strength and abusive power.
When Fitzgerald describes the two different sides, East and West, we see how those from the East are destructive and dishonest, and materialistic (like Tom is). He lies to both his wife and to George, while destroying their lives in the process. He also brags about all he has when Nick first visits their mansion.