At the beginning of the 1900s, automobile drivers signaled to pedestrians and other drivers their intention to turn (or stop) their cars with their hands. As the graphic below illustrates, the hand signal conventions for right and right turns and stop haven’t changed since that time and are still commonly used by vehicles with turn signals.
The first modern turn electric signal can be attributed to Edgar A. Walz, Jr. who, in 1925, secured a patent for one and tried to market it to major car manufacturers. Believe it or not they just weren’t interested and the patent expired fourteen years later.
Interesting, the turn signal situation in Europe started differently. www.hoffmanchryslerjeepdodge.com explains that the solution for signaling turns or lane changes was originally solved with hands signals but later via semaphore indicators. These are mechanical arms known as “Trafficators” mounted on cars. Trafficators were powered by electro magnets that raise an “arm” indicating a turn was about to be made. Once these arms were in the “on” position, power went to the lens, lighting a sbright bulb. When they were “off”, the trafficators folded back into the door pillar. See the image below.