In the early twentieth century, St. Louis was a hotbed for ragtime and blues, both roots of jazz music. In 1914, Jelly Roll Morton brought his music to the area. In 1919, Louis Armstrong came to town to play on the "floating conservatories" that plied the Mississippi. Miles Davis, the most famous of the city's jazz natives, changed the course of the genre four different times throughout a world-renowned career. The Black Artists Group of the 1970s was one of the first to bring world music practices into jazz. Author Dennis C. Owsley chronicles the ways both local and national St. Louis musicians have contributed to the city and to the world of music.