Final answer:
The Johnson-Reed Act of 1924 introduced a quota system that limited immigration from outside the Western Hemisphere based on nationality. It favored immigrants from northern and western Europe and banned immigration from Asia, except for the Philippines.
Step-by-step explanation:
The Johnson-Reed Act of 1924 brought significant changes to U.S. immigration policy. It introduced a quota system that limited the number of immigrants allowed to enter the United States from outside the Western Hemisphere. The quota was based on the number of immigrants from each nationality already living in the U.S. in 1890, resulting in a preference for immigrants from northern and western Europe. The act also banned immigration from Asia, except for the U.S. territory of the Philippines.