In the US specifically

The KKK became a popular organizing force against immigration in this period. I'm from WV and know family history and the history of Senator Robert Byrd who was a KKK member. Many of the areas where KKK strength was greatest were mid western and northern areas where there were large influxes of Italian and other southern Euro immigrant populations. Italians were segregated and not allowed to own land in certain areas. Anti-Italianism was part of the anti-immigrant, anti-Catholic ideology of the revived Ku Klux Klan (KKK) after 1915; the white supremacist and nativist group targeted Italians and other foreign Roman Catholics, seeking to preserve the supposed dominance of Anglo-Saxon Protestants. During the early 20th century, the KKK became active in northern and midwestern cities, where social change had been rapid due to immigration and industrialization, and was not limited to the South. It reached a peak of membership and influence in 1925. The Immigration Act of 1924, or Johnson–Reed Act, including the National Origins Act, and Asian Exclusion Act (Pub.L. 68–139, 43 Stat. 153, enacted May 26, 1924), 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.[1] In addition, it severely restricted the immigration of Africans and outright banned the immigration of Arabs and Asians.