Judy Garland, the first teen idol

Delanceyplace.com has a selection from Teenage: The Prehistory of Youth Culture: 1875-1945 by Jon Savage:

Long before the Beatles hit Shea Stadium, the relatively unknown Judy Garland found herself as perhaps the very first teen idol, and was stunned by the overwhelming reception she received, primarily from teenagers, on a whirlwind publicity tour for the release of The Wizard of Oz. Garland and her frequent co-star, Mickey Rooney, thus helped usher in an age of teenage idols:
The studio had planned The Wizard of Oz as an epic to compete with the market domination of Fox' Shirley Temple, the biggest box-office draw of 1936, 1937, and 1938. It ended up at nearly double the cost of a typical major MGM picture. The studio had some serious recouping to do, and set in motion a massive promotional blitz that began in May of 1939 and continued building over the next three months up to the saturation booking of the film nationwide.
The film's theme tune, Over the Rainbow, had been intended by writers Yip Harburg and Harold Arlen as 'a song of yearning'. Performed by the film's sixteen-year-old female lead, Judy Garland, it was, by August of 1939, the most frequently played tune in the country.
MGM decided to send Judy Garland out on tour to coincide with the film's premiere in each city. The rising star would be accompanied by the country's top juvenile: Garland and Mickey Rooney had already been established as duo in 1938's Love Finds Andy Hardy, and the studio wished to promote the forthcoming musical Babes in Arms. Both were accomplished and popular vaudeville veterans, but no one could have predicted the response that began with the pair's first appearance in Washington on 9 August 1939 and that built over the next three days in Connecticut.
In New York City, the pre-hype reached a crescendo. The competition to be one of the hundred-and-fifty-strong 'official welcoming committee' had attracted a quarter million replies. When Garland and Rooney arrived in Manhattan at midday on 14 August 1939, the selected few were swamped by a 'screaming, delirious, perspiring roped-off mob' of ten thousand fans who filled Grand Central Station. The New York Daily News pictured Judy Garland stretched in a crucifixion pose between two rescuing policeman, her face contorted in a rictus of pain and shock.
On the day of the official opening at the Capitol Theater, the seventeenth, the queue began forming on Broadway at 5:30 am. By the time the five thousand tickets went on sale at 8 am, police estimated that fifteen thousand were outside the theater, eventually forming a line that went five and six deep around the block between 50th and 51st Streets, Broadway and Eighth Avenue. This time, reporters took a closer look at this predominantly female swarm and observed that 'about sixty per cent of the multitude were minors'.
Stunned by their reception, Garland and Rooney quickly recovered themselves and gave their professional best in the dance and vocal numbers that interspersed the performances of the film itself. By the end of the day, they had given seven shows to over thirty thosuand customers, according to the Hollywood Reporter: 'The overflow filled almost all the other Broadway houses, jammed the restaurants, soft drink parlors, and candy stores.' With rave notices, this pattern continued for nearly two weeks until Rooney's final appearance on 30 August: packed performances, jammed streets, mobbed stars."

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