Chinatown, San Francisco
Besides being a snazzy tourist destination, San Francisco's Chinatown plays a huge role in the theme of the story. Waverly (a Chinese American girl) and her mother (an immigrant born and raised in China) both live there, and they almost never leave (except to go to chess tournaments). Why is this important? Because Chinatown stands in between Chinese culture and American culture, just like Waverly and her family.
It's in an American city and a lot of white tourists visit, but Chinese immigrants live there, and their culture is on full display. For example, look at the sign in the fish shop, which "informed tourists, 'Within this store, is all for food, not for pet'" (6), or the restaurant down the block where "Tourists never went […] since the menu was printed only in Chinese" (8). Chinatown, in short, is a cultural crossroads.
Waverly and her family hang in the same balance, and it's possible that some of the tension between Waverly and her mother comes from the fact the Waverly is more comfortable living in that balance than her mom is. For instance, when Waverly has to decide between American and Chinese birthdays—"I was seven according to the American formula and eight by the Chinese calendar" (13)—she doesn't choose one or the other. Instead she simply says, "I was born on March 17, 1951" (13). It works equally well for both cultures without specifically belonging to either one of them. Nicely done, Waverly.
Contrast this with her mom, who thinks American people are "lazy" (12) and doesn't want to belong to their culture. She changes her tune only when it's convenient to her, like when she explains away the unfair chores she gives her sons as "new American rules" (47). She doesn't really integrate into American culture, and in Chinatown she doesn't really have to. Sadly for her, Waverly isn't quite that accommodating.