“Some women and I worked our tails off to get as many women signed up as possible, and we got 78!” recalls Kathrine Switzer, who’d made history five years earlier by running the Boston Marathon. “I realized, if you give women a safe, non-intimidating, welcoming, fun space that’s no judgment, they will show up.” That success led Switzer to launch the Avon International Running Circuit in 1977, which eventually put on more than 400 women’s races in 27 countries.