Why did Chicago jazz arise?

Ideal Answer: The ideal answer should:
1. Explain that the seeds that blossomed into full-bodied jazz culture were planted across America at the turn of the century. The most famous musicians, however, all went to or passed through Chicago.
2. Note that as the Chicago Jazz Age came into its own, Pretty Baby became the city's theme song. It was written by Tony Jackson, whom Jelly Roll Morton (the self-proclaimed inventor of jazz) called maybe the best entertainer the world has ever seen.
3. Point out that the South Side, specifically along State Street between 31st and 35th, was the beating heart of the city's Jazz Age.
4. Conclude that although Chicago did not replace New York as the major location for the aspiring jazz musician, it was the place you went to prove you had what it took to make a name for yourself.