Analysis of information sources in references of the Wikipedia article "歐裔美國人" in Chinese language version.
The 1924 act also sought to curtail the large number of eastern and southern European migrants who began entering the United States in 1890. Through the National Origins Quota formula, the act pegged future immigration at up to 2 percent of the number of foreign-born persons from a particular country already in the United States as of the 1890 census. Through race-neutral in language, the formula favored northwestern Europeans by using the 1890 census as its referent