While New Orleans jazz has improvised ensembles, when jazz started becoming popular in the 1920s and demand was growing for larger dance bands, it became necessary for ensembles to be written down, particularly when a group included more than three or four horns. Although swing largely began when Louis Armstrong joined Fletcher Henderson's Orchestra in 1924 and Don Redman began writing arrangements for the band that echoed the cornetist's relaxed phrases, the swing era officially started in 1935 when Benny Goodman's Orchestra caught on. Swing was a major force in American popular music until the big-band era largely ended in 1946.
