Radio developed in the 1920s and 1930s as a domestic medium, aimed primarily at women in the home, but also playing an important role as general family entertainment, particularly in the evening. Radio in North America was significant for disseminating music in concert form, and
helped bring regionally based forms such as western swing and jazz to a wider audience. Historically the enemy of the record industry during the disputes of the 1930s and 1940s around payment for record airplay, radio subsequently became its most vital promoter. The reshaping of radio in the 1950s was a key influence in the advent of rock’n’roll, while radio airplay became central to commercial success, especially through the popular new chart shows. ‘Hit radio’ was ‘one of America’s great cultural inventions’, revitalizing a medium threatened by television (Barnes, 1988:9). The DJ (disc jockey) emerged as a star figure, led in the United States by figures such as Bob ‘Wolfman Jack’ Smith and Alan Freed.