According to the book, Nick Carraway's rented house and Jay Gatsby's mansion are both located in the fictional village of West Egg on Long Island. West Egg and East Egg are said to be two egg-like formations of land that jut out onto Long Island Sound.
Tom and Daisy Buchanan's house is situated on East Egg, which is separated from West Egg by what Nick calls a 'courtesy bay.' Accordingly, this bay is named Manhasset Bay. Nick describes how he drives over to have dinner with the 'Tom Buchanans' at their Georgian Colonial mansion one evening. There, an attractive young woman, Jordan Baker, reveals to Nick that Tom has a mistress, Myrtle Wilson, who lives in the Valley of Ashes.
Myrtle's husband, George, owns Wilson's Garage, which is situated in the Valley of Ashes, between West Egg and New York City. The Valley of Ashes is so-called because of the thick dust which settles over everything in the industrial district.
This is a valley of ashes—a fantastic farm where ashes grow like wheat into ridges and hills and grotesque gardens where ashes take the forms of houses and chimneys and rising smoke and finally, with a transcendent effort, of men who move dimly and already crumbling through the powdery air. Occasionally a line of grey cars crawls along an invisible track...and immediately the ash-grey men swarm up with leaden spades and stir up an impenetrable cloud which screens their obscure operations from your sight.
According to the story, Wilson's Garage is one of three buildings on a nondescript main street. George Wilson's business involves car repairs and the buying and selling of cars. Ironically, George buys cars from Tom Buchanan, his wife's lover, and resells the cars. According to Catherine, Myrtle's sister, Tom and Myrtle have lived over the garage for eleven years.
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Nicks house is in west egg
The Buchannans house is in east egg (across the sound)
And Wilson's Garage is in the Vally of ashes