The 1965 Immigration Act

Since 1924, US immigration law had set strict quotas by country, calculated to preserve the existing ethnic makeup of the population. That system all but guaranteed most immigrants came from northern and western Europe, like Britain and Germany, while cutting off most of Asia and sharply limiting southern and eastern Europe. By the 1960s, that kind of explicit ethnic favoritism looked out of step with the civil rights movement's push against legal discrimination, so Congress passed the Immigration and Nationality Act of 1965 to get rid of it.

The 1965 act replaced national origin with two new priorities: family reunification, meaning relatives of people already in the US got preference, and employment skills, meaning people with professions or training the economy needed got preference. Lawmakers did not expect this to change much, since they assumed most future immigrants would still be European relatives of earlier European immigrants. That assumption was wrong. Once the door opened on a skills and family basis rather than a national quota basis, immigrants from Asia and Latin America, regions with real demand for entry and ties to the US through family or labor, began arriving in large numbers.

Over the following decades those family chains kept multiplying. One relative admitted under the new rules could sponsor siblings, parents, or children, so small initial numbers from countries like the Philippines, India, Mexico, and Korea grew into major immigrant communities by the 1980s and beyond. The result was a demographic shift the law's authors never predicted, and it reversed four decades of policy built on the 1924 quota system's European preference.