The Harlem Renaissance was important to the United States as a whole mostly because of its effect on African Americans. It was also important to the extent that it had an impact on white culture.
The lesser impact of the Harlem Renaissance came in the way that it impacted white culture. For the first time, whites became very interested in African American music and dance. They started to listen to jazz. They started to dance the Charleston. By doing these things, they were implicitly accepting African Americans as in some way valuable. In the long run, this may have been important.
More important was the impact of the Harlem Renaissance on black America. This was the first time in which a true sense of racial pride arose among African Americans. They had been enslaved and discriminated against and essentially told that they were worthless except as menial labor. The Harlem Renaissance changed that. It made clear that African Americans actually did have something to offer society. Along with the Harlem Renaissance came the “New Negro” who was more assertive and prouder. This sort of incipient black nationalism was bolstered by people like Marcus Garvey who were not exactly part of the Renaissance but were contemporaries. We can say that these new sorts of attitudes later helped to bring about things like the Civil Rights Movement.