In 1970, every Justice on the Supreme Court of Canada was male. Prime Minister Pierre Elliott Trudeau had an all-male cabinet. Canada had never had a female premier - or even a female television newsreader. Little girls across the country were starting to feel the faint stirrings of ambition, often encouraged by mothers who wanted their daughters to live life to the fullest. But they had no idea - how does one be a "career woman"? What does a professional woman even look like?
Then the Mary Tyler Moore Show came along. It showed a woman who was smart, and independent, and made mistakes - and won out in the end. She was successful. She was likeable. She opened up a world of possibilities.
The Mary Tyler Moore Show first aired in 1970, and went off the air in 1977. This is what happened to US female labour force participation rates during this period.