The 1924 Act curbed Jewish and Catholic immigration through race-based national quotas.

Evidence

The deluge of anti-Semitic and anti-Catholic appeals succeeded. The 1924 Immigration Act limited the total number of immigrants to approximately 150,000 per year and restricted immigration from Eastern and Southern European countries to a mere 2 percent of American residents from each country as recorded in the 1880 US Census. Because most Eastern European Jews and Southern European Catholics immigrated after 1880, the law prescribed larger allocations for immigrants from Northwestern Europe. As a result, for the next forty years, 70 percent of immigrants would come from the United Kingdom, Ireland, and Germany. The immigration law also prohibited entry of non-White persons ineligible for citizenship, which targeted Japanese, Chinese, and other Asians but also restricted immigration from the Middle East, as I discuss in chapter 4. — Sahar F. Aziz, The Racial Muslim, 244