Imagine yourself on Seventh Avenue in New York City in the middle of the 1920s. You are a young African American, and you are in Harlem, a thriving center of African American life and culture and the most exciting place in the world to you. It is Sunday afternoon, and the after-church parade has begun. All around you are people of color. They may be rich or poor or middle class, but they are all dressed in their finest clothes. They stroll along, talking, laughing, debating, and enjoying the sights and sounds of their special part of the world.

If you work as a maid or in a factory, you may have attended a "rent party" last night, where you danced to the thumping music of a solo piano player in a...