In 1967, 20-year-old Kathrine Switzer became the first woman to run the Boston Marathon, even though women were not allowed to compete at the time. As she was running, a race official ran up to her and tried to forcibly remove her from the course, captured in an iconic photo by the Boston Globe.
After the race, Switzer advocated for women's sports to be taken seriously and for the women's marathon to be added to the Olympic Games.
"It changed everything," she told NBC News. "It changed my life and it changed millions of women's lives."