How we cite our quotes: (Chapter.Paragraph)
Quote #1
To anyone who saw them averting their eyes from the dark-haired New Yorkers careening past them [...] it was obvious that they were Midwestern and intimidated. (2.1)
This sets the tone for everything to follow. Alfred and Enid aren't just Midwesterners: They're die-hard suburbanites, a.k.a. everything that New York City isn't.
Quote #2
Down at the offices of the Warren Street Journal, where he sometimes felt insufficiently transgressive, as if his innermost self were still a nice Midwestern boy, he took pleasure in alluding to the European statesman he was "cuckolding." (2.637)
This is the first indication that Chip isn't as comfortable on the East Coast as he'd have you believe. We'll be meeting that "innermost self" soon enough.
Quote #3
More typically though, the only discordant note at Deepmire would be an off-color toast offered by some secondary groomsman [...] who sounded as if he didn't come from the Midwest at all but from some more eastern urban place, and who tried to show off by making a "humorous" reference to premarital sex. (2.960)
This quote says two important things: (1) It establishes Enid's belief that Midwesterners have better morals than those East Coast heathens; and (2) it ties the East Coast with urban places, establishing the secondary nature of the rivalry.