That’s my middle-west–not the wheat or the prairies or the lost Swede towns but the thrilling, returning trains of my youth and the street lamps and sleigh bells in the frosty dark and the shadows of holly wreaths thrown by lighted windows on the snow. I am part of that, a little solemn with the feel of those long winters, a little complacent from growing up in the Carraway house in a city where dwellings are still called through decades by a family’s name. I see now that this has been a story of the West, after all–Tom and Gatsby, Daisy and Jordan and I, were all Westerners, and perhaps we possessed some deficiency in common which made us subtly unadaptable to Eastern life.
There’s something moving…in the straightforward phrase: “I am part of that.” Nick’s about to forswear his connection to the east, and to the rich, after he’s spent the whole book trying to establish a place among the elite. It’s not just a beautiful and ennobling image of returning to his origins in the Midwest, it’s the beginning of a kind of rolling movement into the future. Here’s Nick’s telling us that his involvement in the story, this period of his life, ended. In talking about the trains of his youth that took him home, Nick also allows the reader to understand that he’s traveled away from the story. You have this image of train travel, so it’s very literalized. He creates this visual image of leaving the East to go home when he’s young, when he was a student, but he’s making it clear that that’s what he did after this story, too.