Final answer:
African Americans moved to Harlem, Chicago, and Detroit during the Great Migration in the early 20th century seeking better economic opportunities and to escape racial segregation. The migration led to the development of vibrant African American communities.
Step-by-step explanation:
African Americans moved to Harlem, Chicago, and Detroit during the Great Migration in the early 20th century. They were seeking better economic opportunities and to escape racial segregation in the South. The migration led to the development of vibrant African American communities in these cities, such as Harlem becoming the epicenter of the Harlem Renaissance.