The Chinese Exclusion Act of 1882 prevented all but a few Chinese to enter the United States legally. In 1906, a major earthquake and resulting fire in San Francisco destroyed public records, allowing many Chinese to claim that they had been born in San Francisco. These men, with newly established citizenship status, periodically returned to China and claimed citizenship for their children (overwhelmingly boys) who could then immigrate into the United States as citizens. As U.S. officials became aware of this practice, they created extensive “traps” to uncover these “paper sons.” At the Angel Island immigration station (1910-1940) located off the coast of San Francisco, officials detained immigrants for weeks, months, and sometimes years, before admitting or rejecting them. Elaborate “coaching books” were studied by would-be immigrants in order to tell the same stories put forth by the alleged U.S. citizen who was waiting for his “paper son” on the American shores of Gold Mountain. Questions included minute details of the immigrant’s home and village as well as specific knowledge of their ancestors. This coaching book was studied by Choi Tsia who arrived on Angel Island in 1938. Approximately 175,000 Chinese immigrants came through Angel Island.