 In the United States more babies were born during the seven years after 1948 than in the previous 30, causing a shortage of teenage babysitters.Madison, New Jersey, for example, only had 50 high-school girls to babysit for a town of 8,000, and any sitter could have had two sitting jobs at once if desired.$5 of the $7 that a California couple spent to go to the movies in 1950 went to the babysitter.