Final answer:
The rapid urbanization and industrialization of the United States by 1920 created new economic opportunities for women, international migrants, and internal migrants, driving a significant population shift from rural to urban areas.
Step-by-step explanation:
By 1920, the majority of the U.S. population lived in urban centers due to rapid urbanization and industrialization which provided new economic opportunities for different social groups. Among these groups, women, international migrants, and internal migrants, including post-Civil War southern Blacks, all found new possibilities for employment and a better life in the city. Women joined the workforce in large numbers, especially in long-established textile factories. International migrants, influenced by a combination of factors including famine and religious persecution in their home countries, arrived in the United States and often took jobs in urban factories. Similarly, internal migrants left declining rural agricultural prospects for better wages in industrial labor.
These demographic shifts were driven by technological advances such as commercial electricity, which allowed factories to operate more efficiently and increased the demand for industrial workers. From 1880 to 1920, the number of industrial workers expanded significantly from 2.5 million to over 10 million, indicating the extent of the migration to cities. This migration not only altered the labor force but also had profound effects on the urban landscape, culture, and way of life.