The 1924 act was passed due to growing public and political concerns about the country's fast-changing social and demographic landscape.

Henry Cabot Lodge was confident the bill would provide an indirect measure of reducing emigration from these countries, but after passing both houses of Congress, it was vetoed by President Grover Cleveland.

The First Red Scare of 1919–1921 had fueled fears of foreign radicals migrating to undermine American values and provoke an uprising like the 1917 Bolshevik Revolution in Russia.

[11] U.S. Representative Albert Johnson, a eugenics advocate, and Senator David Reed were the two main architects of the act.

They conceived the act as a bulwark against "a stream of alien blood"; it likewise found support among xenophobic and nativist groups such as the Ku Klux Klan.

[15][16] Reed told the Senate that earlier legislation "disregards entirely those of us who are interested in keeping American stock up to the highest standard—that is, the people who were born here.

[15] Eugenics was used as justification for the act's restriction of certain races or ethnicities of people to prevent the spread of perceived feeblemindedness in American society.

He cites their supposed inability to assimilate to American culture and the economic threat that they posed to white businessmen and farmers.

[10] Opposing the act, U.S. Secretary of State Charles Evans Hughes said, "The legislation would seem to be quite unnecessary, even for the purpose for which it is devised.

I realize, as I believe you do, the grave consequences which the enactment of the measure retaining that particular provision would inevitably bring upon the otherwise happy and mutually advantageous relations between our two countries.

"[25] Members of the Senate interpreted Hanihara's phrase "grave consequences" as a threat, which was used by hardliners of the bill to fuel both houses of Congress to vote for it.

Because 1924 was an election year, and he was unable to form a compromise, President Calvin Coolidge declined to use his veto power to block the act,[26] although both houses passed it by a veto-overriding two-thirds majority.

[33][34] However, this did little to diversify the nations from which immigrants came because the 1920 census did not include Blacks, Mulattos, and Asians as part of the American population used for the quotas.

[citation needed] Establishing national origin quotas for the country proved to be a difficult task, and was not accepted and completed until 1929.

[35][page needed] The act gave 85% of the immigration quota to Northern and Western Europe and those who had an education or had a trade.

[34] The act established preferences under the quota system for certain relatives of U.S. residents, including their unmarried children under 21, their parents, and spouses at least 21 and over.

Non-quota status was accorded to wives and unmarried children under 18 of U.S. citizens; natives of Western Hemisphere countries, with their families; non-immigrants; and certain others.

The act also mandated no alien to be allowed to enter the U.S. without a valid immigration visa issued by an American consular officer abroad.

[41] Passage of the Immigration Act has been credited with ending a growing democratic movement in Japan during this time period, and opening the door to Japanese militarist government control.

[42] According to David C. Atkinson, on the Japanese government's perception of the act, "this indignity is seen as a turning point in the growing estrangement of the U.S. and Japan, which culminated in the 1941 attack on Pearl Harbor".

[45] The provisions of the act were so restrictive that in 1924 more Italians, Czechs, Yugoslavs, Greeks, Lithuanians, Hungarians, Poles, Portuguese, Romanians, Spaniards, Chinese, and Japanese left the U.S. than arrived as immigrants.

[56] Even the mass migration of unskilled workers had been a spur to innovation, according to a paper by Kirk Doran and Chungeun Yoon, who found "using variation induced by 1920s quotas, which ended history's largest international migration" that "inventors in cities and industries exposed to fewer low-skilled immigrants applied for fewer patents.

[30] Due to the reliance upon eugenics in forming the policy, and growing public reception towards scientific racism as justification for restriction and racial stereotypes by 1924, the act has been seen as a piece of legislation that formalized the views of contemporary U.S.

[61] U.S. immigration law was cited favorably by the framers of Nazi legislation due to its excluding "wholly foreign racial population masses".