Anna Lee Aldred was only 18 when, in 1939, she became the first American woman to be a licensed, professional jockey.
She was not the first woman to race horses, of course. One notable example, Eliza Carpenter, was born into slavery and according to legend, used her speed on horseback to be the first person to stake a claim on open land in Oklahoma. But Aldred, who was born Anna Lee Mills and grew up in a racing and rodeo family, wanted more than just to race. She wanted the respectability and money that came with pro racing.
Three years before her death in 2006, Aldred recalled to the Denver Post that the officials at the Agua Caliente Racetrack tried to block her application but were unable to find a written rule stating that only men could race. Aldred was issued a license and raced professionally for a few years before switching to rodeo trick riding and, eventually, leaving it all behind after marrying.
Though jockeys still tend to be men, Aldred did start a slow wave of change. In 1968 Kathy Kusner, an elite equestrian, became the first woman to "be licensed to race horses on the flat at a major track where betting is legal," as the Associated Press put it at the time. In Kusner's case, getting the license wasn't as simple as officials not being able to find a rule keeping her out: after the Maryland Racing Commission denied her a license twice, she took her case to court. The judge ruled that the Commission, which claimed that the denial was because she was not strong enough to control a horse, had in fact denied her application purely on the basis on sex, in violation of her civil rights.
As Diane Crump, who would be the first woman to race in the Kentucky Derby, told TIME in 1969, "A horse doesn't know whether the rider on his back wears a dress or pants away from the track."
Aldred's original 1939 license is at the National Cowgirl Hall of Fame, from whose collection these photos are drawn.