The immigration act of 1924 targeted people born in for immigration restrictions

The Immigration Act of 1924, or Johnson–Reed Act, including the National Origins Act, and Asian Exclusion Act, was a United States federal law that limited the annual number of immigrants who could be admitted from any country to 2% of the number of people from that country who were already living in the United States as of the 1890 census, down from the 3% cap set by the Emergency Quota Act of 1921, which used the Census of 1910. The law was primarily aimed at further restricting immigration of Southern Europeans and Eastern Europeans, especially Italians, Slavs and Eastern European Jews. In addition, it severely restricted the immigration of Africans and banned the immigration of Arabs and Asians.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.