Did a quick google search and the very first website I came across echoes what my Jazz mentor has told me.

I typed in "origins of Jazz" and I think it was the third entry down on the list.

Almost straight away (I didn't read any further) it says:

"The origins of Jazz are attributed to turn of the 20th century New Orleans, although this unique, artistic medium occurred almost simultaneously in other North American areas like Kansas City, Saint Louis and Chicago. Traits carried from West African black folk music developed in the Americas, joined with European popular and light classical music of the late 18th and early 19th centuries, became the syncopated rhythms of Ragtime and minor chord voicings characteristic of the Blues."