How does the setting of The Great Gatsby contribute to the theme of the novel?And are there any quotes that show this?

The themes of The Great Gatsby are
quintessentially American: dreams, money, power, morality, love, greed, and gender.  All
of these are connected to the geography of the novel and American
itself.

• East Egg,
  (Port Washington, Long Island NY) where Tom and Daisy live, stands for the "East Coast,"
  the established rich, white collar, the early Puritan white settlers, the
  bourgeoisie who are, according to Nick careless, greedy,
  unfaithful, and immoral.


• West
  Egg, (King's Point, Long Island NY) where Nick and Gatsby live,
  represents the "West Coast," the newly rich, where the "go West young man" settlers
  venture to stake out new bounds.  Though Gatsby is a criminal, Nick forgoes judgment and
  lives vicariously through Gatsby's American
  dream.


• The Valley of Ashes,
  (Flushing Meadows, Queens NY) where George and Myrtle live, represent the "Middle West,"
  where the proletariat (working class, blue collar) live, full of dust and death.  This
  is where the American dream goes to die (it's where Gatsby's dream dies, when Daisy hits
  Myrtle).  The Eyes of T. J. Eckleburg haunt the place, reminding us of a God who
  abandoned.  What used to be idyllic and charming about the Midwest (in the Louisville
  flashbacks) is now dust.  Eventually, Nick will return to the Midwest (Minnesota), where
  he narrates the novel two years after Gatsby's
  death.


• New York City, (158th
  St. Manhattan, NY) where Tom keeps his mistress Myrtle, is a sordid place full of
  brutality (Tom's slap of Myrtle), decay (Meyer Wolfsheim's human molar cufflinks),
  murder (Meyer Wolfsheim's story of Rosie Rosenthal's murder), and oppressiveness (the
  heat).