Final answer:
Religious persecution acted as a push factor for millions of immigrants from eastern and southern Europe, leading them to seek refuge in the United States. They fled to escape discrimination and sought the economic opportunities and freedom America offered. The U.S. assimilated a diverse group of immigrants and served as a safety valve for Europe.
Step-by-step explanation:
Religious persecution in various countries in Eastern and southern Europe served as a push factor for millions of immigrants who fled to the United States. This persecution led to the migration of many Eastern European Jews and Roman Catholics throughout Europe, seeking refuge and a new life in America, free from discrimination and violence. The mass emigration was also driven by various push and pull factors, including ongoing famines, political oppression, compulsory military service, and the attraction of available work and economic opportunity in the U.S.
America served as a 'safety valve' for European nations, absorbing a significant number of poor landless peasants, thereby alleviating some of the population pressure back in Europe. The diversity and promise of America attracted a wide array of immigrants, including Italians, Greeks, Russians, and Jews from Eastern Europe, amplifying its role as a melting pot and bolstering U.S. neutrality in European affairs.