You might find this interesting:

http://www.reddit.com/r/AskHistorians/comments/1ncalm/was_jazz_a_reaction_to_classical_music/cchfcpg

Jazz certainly did evolve out of the folk musics of the American south, and the blues definitely played a massive part in its formation. "Jazz" is essentially a synthesis between ragtime, march music, the blues, spanish and cuban musics, fiddle/string band music, church music of all kinds, and more! The link above goes in to more detail on the subject. Check out these links for a some examples of the music that inspired jazz. Let me know if you want some examples of anything specific, I can do that.

Sonny Terry and Brownie McGhee

Birmingham Jubilee Singers

Second Zion Four

John Sousa

Now watch what happens when a Black-American military band played a march with their own adaptions. They "ragged" it:

James Europe
Paul Whiteman is generally considered pretty cheesy and un-swinging, but he was really influential.

Paul Whiteman

hi! not discouraging the music historians from contributing direct responses, but you may be interested in some previous posts on the origins/history of jazz:

• Was jazz a reaction to classical music?

• What is the historical context that spawned jazz?

• Why has African american style music become pop music in some shape or form?

• examples: How popular and mainstream was jazz music in its prime?