| Smithsonian Institution

Until the 1970s, women were barred from competing in U.S. marathons because of the belief that the "violent movements" of running would wreak havoc on their reproductive system, "thus defeating a woman’s true purpose in life, i.e., the bringing forth of strong children." Through a series of steps, stumbles—and one epic tackle—running pioneers like Roberta "Bobbi" Gibb and Kathrine Switzer blazed the trail for women marathoners who followed, including Sunita Williams—the first person to run the Boston Marathon in space!