Although reliable numbers are difficult to come by because most Fujianese are here illegally , it is estimated that 300,000 immigrants from the Fuzhou region are in the United States , with the largest concentration , about 60,000 to 70,000 , in New York City , said Kenneth J . Guest , a Baruch College anthropology professor who wrote the book '' God in Chinatown '' -LRB- New York University Press , 2003 -RRB- .