The Library of Congress has a great description of the music scene at the World’s Fair. Dvorak was there conducting, Sousa was there leading his band. Will Marion Cook (later Duke Ellington’s mentor), and Joseph Douglass (grandson of Frederick Douglass) performed. Scott Joplin, then living and working in Chicago likely played ragtime in one or more of the numerous saloons and cafes along the outskirts of the fair.
25 million visitors from hundreds of countries soaked it all in, and carried the new popular musical styles home across the US and abroad.