2. The Immigration Act of 1924: This law established a system of national quotas, which limited the number of immigrants from each country that could enter the United States each year. The quotas were based on the national origin of the population in the United States in 1920. This law discriminated against immigrants from Eastern Europe and Southern Europe, who were perceived to be less desirable than immigrants from Northern and Western Europe. The Immigration Act of 1924 also introduced the concept of "alienage," which made it difficult for immigrants to become naturalized citizens.