By the end of the 19th Century, huge numbers of Jews wanted to emigrate from Eastern Europe. Zionism—the belief in creating a Jewish nation-state in Palestine–arose as one possible destination. However, Palestine belonged to the Ottoman Empire, which opposed European immigration to its territory. As a much-to-be-preferred alternative among the emigrants, 4 million of them came to the United States between 1880 and 1920. Then, the Ottoman Empire joined Germany and Austria-Hungary during the First World War. In a moment of desperation, Britain announced its support for the creation of a “Jewish national home” in Palestine.
In 1922, two leading Republican foreign policy experts, Henry Cabot Lodge and Hamilton Fish, sponsored a Congressional resolution supporting a Jewish homeland in Palestine. Walter Russell Mead sees this resolution as “launching a tradition of official American support for Zionist aspirations in Palestine that a long line of presidents from both parties have continued.” However, Lodge strongly opposed immigration from Southern and Eastern Europe. He helped write the immigration law of 1917 that began the restricting of immigration. That process peaked in the Immigration Act of 1924, which cut Jewish immigration by 90 percent.
In the Thirties, Arab nationalist resistance to European immigration, which turned violent just as Britain tried to deal with the prospect of wars with Germany, Italy, and Japan, led Britain to slam the brakes on most further immigration.
In the wake of the Holocaust, In June 1945, the Jewish Agency in Palestine asked the British government to admit 100,000 Jews in European refugee camps to Palestine. Sensitive to the hostile Arab response, the British declined. In August 1945, after a brief survey of the camps by an American delegation, President Harry Truman asked the British to admit 100,000 survivors of the Holocaust to Palestine. Again the British resisted. Truman could have passed the issue to the newly-established successor to the League of Nations, the United Nations. He did not. He pressed for creation of an Anglo-American Commission of Inquiry. The commission worked in the shadows of the prospective negotiations over an American loan to a bankrupt Britain. It should surprise no one that Truman used the commission’s report to successfully pressure the British to admit 100,000 Jewish refugees to Palestine.
After the war, most Americans remained deeply opposed to increased immigration. In December 1945, Truman used a Presidential directive to by-pass Congress: Displaced Persons were accorded priority within the existing quota system. As a result, 35,000-40,000 Jewish refugees were admitted by mid-1948. Only after Israel was established and recognized by the United States, did a series of Displaced Persons Acts (1948, 1950, 1953) allow some 600,000 refugees into the country. Of the almost 400,000 admitted by 1952, only 16 percent were Jewish (i.e. about 60,000). In the same period Israel took in over 600,000 people.
It is possible that early American support for Israel sprang from ugly anti-Semitism.
 Known as the “[Sir Arthur] Balfour Declaration” after the British Foreign Secretary who announced the policy.
 Walter Russell Mead, “A Century of U.S.-Israel Ties,” WSJ, 6 September 2022.
 See: Immigration Act of 1924 – Wikipedia
 See: Anglo-American loan – Wikipedia
 100 years of Aliyah (Immigration) to Mandatory Palestine and the State of Israel, between 1919 and 2020 – Aliyah – Wikipedia