Conversation so far:
what provided the immediate impetus for the niagara movement
The Niagara Movement's beginnings may be traced to the publication in 1903 of The Souls of Black Folk by W. E. B. Du Bois.
What was covered in W. E. B. Du Bois's The Souls of Black Folk?
The Souls of Black Folk is a seminal work in the history of sociology and a cornerstone of African-American literature containing several essays on race.
Is W. E. B. Du Bois famous?
Du Bois was one of the founders of the National Association for the Advancement of Colored People in 1909.
What is the purpose of the National Association for the Advancement of Colored People?
The NAACP's mission is to ensure the political, educational, social, and economic equality of rights of all persons and to eliminate race-based discrimination.“

Question: How many people are members?
Self-contained rewrite: How many NAACP members are there?