http://en.wikipedia.org/wiki/Chinese_American
Language
Chinese, mostly of the Cantonese variety, is the third most-spoken language in the United States, almost completely spoken within Chinese American populations and by immigrants or the descendants of immigrants, especially in California.[33] Over 2 million Americans speak some variety of Chinese, with Mandarin Chinese becoming increasingly more common due to immigration from mainland China and Taiwan.[33]
In New York City at least, although Mandarin is spoken as a native language among only ten percent of Chinese speakers, it is used as a secondary dialect among the greatest number of them and is on its way to replace Cantonese as their lingua franca.[34] In addition, the immigration from Fujian is creating an increasingly large number of Min speakers. Wu Chinese, a Chinese language previously unheard of in the United States, is now spoken by a minority of recent Chinese immigrants, who hail from Jiangsu, Zhejiang, and Shanghai.
Although Chinese Americans grow up learning English, some teach their children Chinese for a variety of reasons: preservation of an ancient civilization, preservation of a unique identity, pride in their cultural ancestry, desire for easy communication with them and other relatives, and the perception that Chinese will be a very useful language as China's economic strength increases. Cantonese, historically the language of most Chinese immigrants, is the third most widely spoken non-English language in the United States.[35]