On May 26, 1924, the U.S. government enacted the eugenics-inspired Immigration Act of 1924, which completely prohibited immigration from Asia. Designed to limit all immigration to the U.S., the act was particularly restrictive for Eastern and Southern Europeans and Asians. Upon signing the act into law, President Calvin Coolidge remarked, “America must remain American.”

In 1917, Congress had passed a highly restrictive immigration law that required immigrants over age 16 to pass literacy tests and excluded immigrants from the “Asiatic Barred Zone.” Immigrants from China had been barred since the Chinese Exclusion Act of 1882, and this law expanded that ban to include many other Asian countries. The Act of 1924 eliminated immigration from Japan, violating the so-called “Gentleman’s Agreement” that had previously protected Japanese immigration from legal restrictions.

The 1924 Act also tightened the national origins quota system. Under this system, the number of immigrants allowed to come to the U.S. from a particular country was limited to the percentage of immigrants from that country already living in the U.S. The previous quota was based on population data from the 1910 census, but the 1924 Act based the quota on the 1890 census, which effectively lowered the quota numbers for non-white countries. The 1924 system also considered the national origins of the entire American population, including natural-born citizens, which increased the number of visas available to people from the British Isles and Western Europe. Finally, the 1924 Act excluded any person ineligible for citizenship, formalizing the ban on immigration from Asia based on existing laws that prohibited Asian immigrants from becoming naturalized citizens.

The act was supported by federally funded eugenicists who argued that “social inadequates” were polluting the American gene pool and draining taxpayer resources. Its quotas remained in place until 1965.