Pew also reports that since 1965, foreign-born immigrants have been the main driver of U.S. population growth as well as demographic change. The report argues that 1965 saw a major shift in immigration policy with the passage of the U.S. Immigration and Nationality Act signed by President Lyndon B. Johnson.
The 1965 law changed the criteria for immigrants admitted to the United States. Before 1965, quotas were assigned to countries based on how nationalities were represented in the census. According to Pew, 70 percent of visas were reserved for immigrants from Europe, primarily the United Kingdom, Ireland, and Germany. Prior to 1965, 80 percent of immigrants were white.
However, the new immigration system abandoned national origin quotas, and instead focused on bringing in relatives of U.S. citizens, as well as taking in immigrants based on their skills in the workplace.