Final answer:
The acceleration of urbanization was an important effect of migration before and after World War I. The Great Migration and globalization contributed to a significant population shift from rural to urban areas and the intertwining of economic and social networks worldwide.
Step-by-step explanation:
An important effect of the migration just before and after World War I was D) the acceleration of urbanization. This era saw significant shifts in populations including the Great Migration, where many Southerners, including a large population of African-Americans, moved from rural Southern states to urban areas in the Northeast, Midwest, and West. As a consequence, cities grew rapidly which imposed a strain on municipal services and intensified the demand for labor in industrial settings, contributing to a change from an agriculture-based economy to an industrial one.
The Great War further influenced migration patterns and the spread of technology and culture through globalization. Despite the disruption caused by the conflict, the continued process of globalization facilitated exchanges of peoples, ideas, and technology, weaving an interconnected economic and social fabric that spanned the globe.