“A car to me is something that is almost human, something that responds to kindness and understanding and care, just as people do,” the actress Florence Lawrence told a reporter in 1920, when driving had become a symbol of women’s liberation. “The average woman does her own repairing. She is curious enough to investigate every little creak and squak of her car, and to remedy it.” Lawrence herself addressed more than squaks: in 1914, she developed an early version of the turn signal. “I have invented an ‘auto-signaling arm,’ which, when placed on the back of the fender, can be raised or lowered by electrical push buttons,” she told The Green Book Magazine. “The one indicating ‘stop’ works automatically whenever the foot brake is pressed.”

Lawrence, whose mother patented a “cleaning device” for windshields in 1918, never patented her own invention and has been largely forgotten in the annals of auto history. As it happens, she has also been forgotten as arguably the first film star. “She’s the beginning of Hollywood,” Kelly Brown, Lawrence’s only biographer, said. “The star system, you can trace it back to these original ads that she was in.”

The “Biograph Girl,” as she was known, based on her work with the film company, wasn’t the very first person to come up with a turn signal. In 1909, a British man named Percy Douglas-Hamilton patented a set of hands, one attached to each side of the car, which could be illuminated to indicate a coming turn. “People look at and cite that patent” as the first, said John Heitmann, a professor at the University of Dayton who specializes in automobile history. “But nothing happened.” He added that it would be “highly unlikely” that Lawrence knew about it. More patents followed — in 1925, Edgar Walz Jr. patented a light with two arrows and a brake light; in the late ’30s, Joseph Bell patented the first electrical device that flashed — and then in 1939, Buick introduced turn signals as a standard feature. Still, electrical turn signals didn’t become widespread until the early to mid-1950s. Before then, a host of makeshift and accessory devices, as well as hand signals, sufficed.

We might not owe the turn signal to Lawrence, but her place in auto history points to something larger. “We always see the automobile as a masculine object, but in fact,” Heitmann said, “women played an active role in thinking about the automobile. That’s where, I think, Florence Lawrence really stands out.” Or, in Lawrence’s own words: “There are as many women driving cars as men. And infinitely better drivers they make too.”