Sikhs began immigrating to the United States in the 1900s. They came as farmers and laborers. The first Gurdwara (place of Sikh congregation) was set up in California in 1906.
In the 1960s, the US government raised its immigration quotas, and the US economy demanded that the country welcome trained professionals with open arms. With other South Asians, Sikh doctors, engineers etc., immigrated to the USA in large numbers.
In the 1980s yet another wave of Sikh immigration took place when anti-Sikh pogroms and government policies rocked the Indian part of Punjab and caused many Sikhs to flee to the United States for safe haven.