Jazz music spread from New Orleans with the Great Migration of African Americans in search of improved economic opportunites during World War I. It was pioneered by Handy "Jelly Roll" Morton and Joseph "Joe" King Oliver, both blacks, but all-white bands, such as the one led by Paul Whiteman, soon followed. W.C. Handy's "St. Louis Blues" became an instant classic. Jazz captured the spirit of the time, and even today it is considered classical American music. The blossoming African American communities in the North witnessed a new sense of racial pride. In New York City, with about 100,000 African American residents during the 1920s, Harlem became one of the largest black communities in the world. A new spirit of of artistic, cultural, and social creativity soon flourished. Whites flocked to the Cotton Club in Harlem and nighclubs on the south side of Chicago, such as the Savoy, to witness performances by Duke Ellington, Louis Armstrong, Honore Dutrey, Baby Dodds, King Oliver, Lil Hardin, Bill Johnson, and Johnny Dodds. Alain Locke, a black intellectual, believed political and social advancement could be made through the arts. The United Negro Improvement Association (UNIA) was founded by Marcus Garvey, also from Harlem. He promoted the resettlement of African Americans to their "African Homeland" and went so far as to sponsor the Black Star Steamship Company. His goal was essentially to keep blacks' dollars in their own pockets while promoting the "back to Africa" movement.