In 1935, swing music became popular with the public and quickly replaced jazz as the most popular type of music (although there was some resistance to it at first). Swing music is characterized by a strong rhythm section, usually consisting of a double bass and drums, playing in a medium to fast tempo, and rhythmic devices like the swung note. Swing is primarily a kind of 1930s jazz fused with elements of the blues and the pop sensibility of Tin Pan Alley. Swing used bigger bands than other kinds of jazz had and was headed by bandleaders that tightly arranged the material, discouraging the improvisation that had been an integral part of jazz. David Clarke called swing the first "jazz-oriented style (to be) at the center of popular music ... as opposed to merely giving it backbone". By the end of the 1930s, vocalists became more and more prominent, eventually taking center stage following the American Federation of Musicians strike, which made recording with a large band prohibitively expensive. Swing came to be accompanied by a popular dance called the swing dance, which was very popular across the United States, among both white and black audiences, especially youth.