Editor's note: Although no one has pinpointed when the music we now can jazz coalesced into an idiom, a September 1995 symposium held in New Orleans celebrated the 100-year mark. Scholars will continue debating the origins; however, few would dispute that the seminal idiom in New Orleans has maintained a distinctive character and sound. It has also undergone a great many changes. With this issue we begin a series on traditional jazz by Jason Berry, who has chronicled rhythm-and-blues and M...