How is the physical journey in The Great Gatsby an important element and how does it add meaning to the story?

The only character who I think makes any significant "physical journey" is Jay Gatsby. We learn later in the novel, after his death, that he grew up poor in the Midwest. Through hard work and exceptional discipline, however, Gatsby saved money, used his experience as a soldier in World War I to study at Oxford, then returned to the United States and worked for Meyer Wolfsheim as a bootlegger in New York.
Gatsby's physical trajectory is similar to that of Fitzgerald, who came from the Midwest (St. Paul, Minnesota), entered World War I as a second lieutenant, then returned to America to write and live in New York. Some of his other characters perform a similar physical journey. Dexter Green, the protagonist of "Winter Dreams," comes from small-town Minnesota, goes to an Ivy League university in the East, returns to Minnesota and enters the laundry business (a successful venture that is briefly interrupted by the war), then moves to New York to expand his wealth.
The importance of these physical journeys is that they are key to the characters' attainment of the American Dream—that is, the journey is what allows them to become upwardly mobile, though Gatsby's path to upward mobility (i.e., bootlegging) is illegitimate and becomes a way through which Tom Buchanan shows Daisy that Gatsby is unsuitable for her. In this way, Fitzgerald exposes the hypocrisy of the upper class, which partakes in drinking the liquor that was illegal at the time (Buchanan drinks liquor while with his mistress Myrtle) but thinks it improper that Gatsby helps to sell it.
Gatsby's physical journey could also be read as key to his downfall. Fitzgerald's work is hopeful about the American Dream but skeptical of its promises. He wants to believe that smart and ambitious people like Gatsby can succeed and belong among the wealthy class but is skeptical that they can be fully accepted.