Final answer:
The African American population in New York City doubled during the 1920s due to the Great Migration from the South, resulting in Harl`em becoming a center for African American culture.
Step-by-step explanation:
The Black population of New York City doubled during the 1920s due to the Great Migration of African Americans from the South.
This resulted in Harl`em, a neighborhood in Manhattan, becoming a center for A f ro-centric art, music, poetry, and politics. The increase in New York's African American population was a significant demographic change during this time period.