If you've ever visited New York City, you'll recognize many of the locations in The Earth, My Butt, and Other Big Round Things. If you live there, you'll probably recognize them all.
Virginia lives on the Upper West Side, in a penthouse apartment on Riverside Drive (read: her family is rich), and Brewster, her elite private school, is on the Upper East Side. She hangs out in Central Park, her mom is interviewed at the 92nd Street Y (as in YMCA), her crush Froggy takes trombone lessons at Juilliard, and her brother goes to school at Columbia University. In other words, all the drama takes place within a matter of blocks.
However, two brief but important chapters take place in Seattle, where Virginia goes to visit Shannon on Thanksgiving break. You could say she finds her true self there, or at least begins the journey toward finding it. She buys a ticket without permission, gets her eyebrow pierced on Capitol Hill, and calls Byron a rapist out loud for the first time, so while she may only spend a short time there, Seattle is an important setting in this book.