Jazz has been called the one truly American style of music. It developed in the South, especially in New Orleans and migrated north during the Great Migration of blacks from south to north at the beginning of the 20th century.
Jazz was originally music by and for blacks, but the radio and phonograph introduced the music to a wider audience. Artists like Louis Armstrong and Duke Ellington became national celebrities. White musicians such as Benny Goodman integrated jazz bands in the 1930s.
After World War II, jazz developed a new style known as be bop, with unusual chords and syncopated styles. Charlie "Bird" Parker, a trumpeter, became the best known of the be bop musicians. Dave Brubeck developed a mass following for his piano stylings, including his use of unusual rhythms. His album "Time Out," featuring the cut "Take Five" in 5/4 time, became the first jazz album to sell a million copies.