The period preceding the United States v. Bhagat Singh Thind Supreme Court case, which determined that "Asian Indians" were ineligible for citizenship on the basis of race.
The period between the Immigration Act of 1924, which severely restricted the number of South Asian (Indian and Ceylonese) immigrants to the U.S., and the Luce-Celler Act of 1946, which raised the quota of Indians allowed in the U.S. to one-hundred per year.
The period following the Immigration Act of 1946 and preceding the Immigration and Nationality Act of 1965, which lifted the restrictions of immigrants based on national origins and led to an increase in skilled laborers from South Asia, among other world regions.
The period following the Immigration and Nationality Act of 1965 and preceding the year 2000.
Current period marked by the era following the September 11, 2001 attacks and the war on terror.