The immigration act of 1965 otherwise known as the Hart-Cellar Act was the first major rewrite of American immigration policy since 1924 when immigration quotas based on national origin were first imposed. Those original quotas had limited immigration based on the population of the US in 1880 and were primarily designed to restrict the immigration of Italians and Jews. AS a result of that act most of the immigrants to the United States in the post-war years were from Western Europe and England.

With America in a global war with communism, the immigration law was seen as an impediment to spreading American values and influence. The new act kept the national quotas in place for three transitional years. During that period those not used were put into the pool. From 1968 onward the quotas were eliminated.

The number of immigrants was initially limited to 170,000 a year. According to the law, up to 20% of the visa will be issued to children of US citizens. The next category were children of immigrants who could get another 20%. Next came professions that were in demand in the United States they received 10 %. The next 10% went to spouses of US citizens. The next specified groups were brothers or sisters of US citizens. They were allocated up to 24% of the total. Next on the list were workers who had trades that were in demand in the US. The final group specified in the new law were refugees either from political persecution or from natural disasters.

The bill passed overwhelmingly with bipartisan support. It passed the Senate 76-18 and the House 320 to 70. President Johnson signed the bill into law on October 3, 1965.

The authors of the bill claimed that the effect of the law would be small. They believed it would not have a significant impact on American demographics. They were wrong. Over the period of time, the bill changed the nature of immigration. As a result of the law, immigration from Asia and South America soon exceeded the immigrants from Western Europe. Over time the number of immigrants was also increased as well. The result over the decades was a significant change in American demography.