The invention of the turn signal involved multiple contributors over time:
- Florence Lawrence, a silent film actress, created the first mechanical turn indicator around 1914. Her design featured an "auto signaling arm" on the car's rear fender that could be raised or lowered by the driver pressing buttons inside the car to indicate a left or right turn. She also created a full-stop signal activated by the footbrake. However, she never patented these inventions
- Percy Douglas-Hamilton patented an early signaling device in 1909, which used illuminated hand-shaped signals to indicate vehicle movements, based on hand signals drivers used at the time
- Edgar A. Walz Jr. patented the first modern electric turn signal in 1925, which included flashing arrows and a brake light. Despite his efforts, car manufacturers were not interested, and his patent expired after 14 years
- Oscar J. Simler invented and patented a turn signal device in 1929 that not only signaled turns but also indicated slowing and stopping by using brake and clutch pedals. His hand-built prototype is housed in the National Museum of American History
- The first factory-installed flashing turn signals appeared on Buick cars in 1939, marking the beginning of widespread adoption of the modern turn signal system
In summary, while Florence Lawrence pioneered the first mechanical turn signal and Oscar J. Simler patented a multifunctional signaling device, the modern electric turn signal concept is credited to Edgar A. Walz Jr. The full development and adoption of turn signals evolved through these innovations over several decades.
