The Jews were not like the Poles, Italians or Germans who arrived with them in New York harbor:
Polish or German families sent their young men ahead of the family to establish themselves and make the family’s arrival more comfortable. Italians who found the immigrant life too difficult returned to their home country in large numbers.
But Jews behaved differently. Once they decided to leave, they sold everything, boarded ships and arrived on America’s shores as whole families. They knew they would not be returning.
During the Panic of 1907, 300,000 Italian immigrants returned home to Italy.
[..]
European immigrants returned to their home countries in huge numbers between 1908 and 1925: 57% of Italians, 40% of Poles, 64% of Hungarians, 67% of Romanians and 55% of Russians.
Among Jews, the figure was just 5%.
[…]
In 1910, when the US had already absorbed some two million East European Jews, New York Immigration Commissioner William Williams ended his annual report with a warning: “The time has come when it is necessary to put aside false sentimentality in dealing with a question of immigration, and to give more consideration to its racial and economic aspects and in deciding what additional immigrants we shall receive, to remember that our first duty is to our country.”
[…]
In 1921, the US Congress decided to act. It passed the Emergency Quota Act and then the 1924 Quota Act, severely reducing Jewish immigration from over 120,000 per year to under 3,000 a decade later.