In the world of classical music, the beginning of the 20th century marked the decline of sweeping Romantic period symphonic compositions. World War I brought about a philosophical change in many artistic circles. Noted composers such as Arnold Schoenberg preferred to portray their world in a dark, realistic context. The music they created was void of traditional harmonic structure and form. Although atonality would later fall out of popularity, many composers adopted this method of composition in reaction to the chaos and destruction they had witnessed in the world's first global conflict.
Increasing levels of artistic commercialization helped augment the popularity of musical theater in the United States. A distinctly American art form, the musical became America's answer to centuries of operatic tradition in western Europe. New York City became the home of American musical theater, and the "Broadway musical" was transformed into the one of the United States' premier entertainment mediums. Popular musicals from the '30s and '40s include Irving Berlin's "Louisiana Purchase" and Cole Porter's "Something For The Boys."
Several distinct musical genres evolved out of "jazz" in the first half of the 20th century. Big band and swing music dominated live music clubs and jazz halls up into the 1940s. The invention of be-bop by Charlie Parker and Dizzy Gillespie in the early '40s produced a more formal, advanced derivative of jazz that existed in sharp contrast to the accessible sounds of its predecessors. Jazz performance in the first half of the 20th century highlighted the paradox of racial division in the United States. Many jazz clubs in New York City only allowed caucasian patrons to enjoy the music of the talented black musicians on stage.