A useful summary of the immigration literature:
The effect was felt at both the state and federal level. Twenty-four states passed laws encouraging sterilization of those who were retarded, insane, or had criminal records. At the Federal level, in 1921, Albert Johnson, head of the House Committee on Immigration and Naturalization, began a series of hearings on immigration. He appointed Harry Laughlin, who in 1922 would be one of Grant's co-founders of the American Eugenics Society, as an expert witness on eugenics. In 1922, Laughlin reported extensively on racial differences in IQ as measured by the new army intelligence test.
In 1923, Grant's close friend Henry Fairfield Osborn, the famous paleontologist who named “tyrannosaurus rex,” spoke enthusiastically about intelligence testing: “We have learned once and for all that the Negro is not like us.”
Congress restricts immigration.
This was precisely the kind of thing Grant and others had been saying for years. These ideas helped pass the Johnson Act of 1924, which established national origin immigration quotas of 2 percent of the number of foreign-born already in America as determined by the census of 1890. This greatly reduced the flow of immigrants from non-traditional sources, a policy that remained essentially unchanged until 1965.