What form of African-American music was said to start in the late 1800s?

In this article by Rev. D.A. Graham, what does he write about the effects of separate accommodations upon young African American men? [See http://www.blackpast.org/1899-reverend-d-graham-some-facts-about-southern-lynchings ]

Who wrote A Red Record. Tabulated Statistics and Alleged Causes of Lynchings in the United States, 1892-1893-1894?

What form of African-American music was said to start in the late 1800s?

Bonus Question (2 points):  What is the name of the most popular Ragtime Music composer? [Hint:  He also wrote an opera called Treemonisha.]

1900-1940